Riding Lawn Mower Won’t Start No Clicking
A riding lawn mower is like a small tractor that cuts grass. And like any automotive it is bound to have some issues. This is because it relies on a fuel powered engine to work. Keep reading to learn how to fix a lawnmower won’t start.
Riding Lawn Mower Won’t Start No Clicking
The most common reason for a no start, not even a click sound, is a totally flat battery, but other likely causes include:
- Transmission in Drive
- Brake Pedal not Pressed
- Blade Switch / Lever On
- Not Sitting in Seat
- Bad Battery Connection
- Sensor Faults
- Flat / Faulty Battery
- Main Fuse Blown
- Faulty Ignition Switch
- Faulty Control Module
Note: A tractor mower won’t start if the blade lever/button is on, manual mowers need to be in Neutral gear, some mowers won’t allow starting if the oil level is low or the hood is open.
Troubleshooting steps to fix a mower that won’t start
Check Battery & Connections
To test a battery you need a voltmeter, but if you don’t have one try this basic check. If your mower has hood lights, or dash lights go ahead and turn them on. If they light up and are bright, your battery is most likely not the problem.
Battery Check Hack
- Turn on the lights to check for power supply
- If they work – the battery is likely OK
- If lights are dim – check battery cables
- If cables clean and tight – charge battery
- If you have no lights – check battery with a volt meter
Perform a Volt Check
You will need a voltmeter for this test. Check battery voltage – 12.65v is 100%, 12.30v is 70%, 12.05v is 50% charged. This battery needs a charge.
Very low volts indicate it’s likely the battery is faulty and it may not recharge. To test a battery it must be charged, for that, a battery charger is required. However, it is possible to jump-start the mower (see below), and given time the mower’s alternator will charge the battery, assuming it isn’t faulty.
Once the battery is sufficiently charged, (about 70%) try the crank test.
Battery crank test
- Battery Crank Test – Attach the Voltmeter and crank over the engine, if the volts read less than nine, replace the battery. (The battery must be over 70% charged to run this test)
- Voltmeter – If the lights don’t work at all, you’ll need to use a voltmeter to check the battery state of charge. You may have a blown fuse.
If you have very low volts, it’s likely the battery is faulty. The average life of a battery is 4 years, more if well cared for.
If you don’t have a charger, you can still get it running but you’ll need a set of jumper wires and a car or any 12volt battery will do the job. Follow this link for a more detailed guide to Jump Starting.
Add the cables in sequence 1, 2, 3, and 4 to start the mower, and while idling remove jumper cables in reverse order 4, 3, 2, and 1.
If Dash Lights are Dim
- Check – Check the battery cables, they should be clean and tight. When connections are loose or corroded, it prevents available power from flowing to the starter.
- Charge Battery – If your battery is completely flat, it will take a couple of hours.
If Dash Lights Don’t Work;
- Check the mower main fuse.
Some mowers will have the blade type fuse, others will have the old style bottle type. When the fuse blows, all power is lost, changing it is simple. It is important to replace the fuse with the correct amp rating. If the fuse keeps blowing – the fuse rating is too low or there’s a short-to-ground wiring fault.
Fuse Location – Places they like to hide include, under-seat, under the hood, behind the fuel tank, incorporated into the Control module. Modules are usually under the dash panel.
Replacing the fuse is simple, just pull out the old one and push the new one into place. It’s important to replace it with the correct amp rating, otherwise, you can damage the wiring circuit and components.
2. Check Safety Sensors
Riding mowers are designed with safety features built in to protect us from operator error or accident. Safety features on mowers are controlled by sensors/switches and most modern mowers will wire those sensors into a control module.
The sensors are a very simple on/off switch type and rarely give trouble, it’s more common for the striking plate that pushes on the sensor to be misaligned, when this happens, the sensor is open and the engine won’t start or stops depending on where the sensors fitted.
Over-riding – Sensors can be overridden for test purposes, remove and join the wires, some sensors are wired in reverse – meaning, just disconnecting them will override the sensor. You can check sensors for continuity using a voltmeter.
Safety sensors are fitted to the seat, blade engages lever or button, transmission selector, brake pedal, and on some models the hood. Any of these sensors will prevent your mower from starting.
On older manual transmission mowers the gear selector wears and although the selector points to the Neutral position, it’s often still in gear – confirm it’s in Neutral by pushing it forward or back, it should be easy to push.
Sensors – These older style Craftsman / Jonsered / Husqvarna blade levers cause lots of no-start problems.
The lever spring gets weak and leaves the sensor in the open position which prevents starting.
Sensors – The quick fix, hold down the lever to start the mower. The complete assembly is available and not too difficult to fit. Check that all sensors are working, look to see the striker plates are closing the sensors fully.
Check wiring to sensors for chafing and that the connectors are secure and free from corrosion.
As you know, there’s a starting procedure which must be followed before your mower will start.
There are several sensors that must be engaged, the location and number of sensors are dependent on the make of the mower and differs between manual and hydro-static (type of transmission).
The main sensors are: brake pedal; seat; gear lever; blade engage control switch or lever and some models such as John Deere will have one fitted to the hood (Hood open – no start).
Jumpstart Mower is the fastest solution, but it may not be the long-term fix.
Check Control Module
Most modern mowers will have a Control module, they are a printed circuit with relays and resistors – they do give trouble.
The function of the control module is to receive a start/stop command from the ignition switch, and only out-put a start command to the starter (via the solenoid) if all the correct sensors have been engaged.
You can visually inspect these modules for loose connections or water damage to the printed circuit. All modules will have a fuse either internal or external – Check it.
As said, all modules will have a fuse either internal or external. As you know the main fuse in a mower can blow, and if it does, it will kill the power to the ignition system.
Modules could be fitted anywhere, they are usually fitted inside a hard plastic box about the size of a mobile phone. Not all mowers will have one fitted, but most will.
Module – Wires come loose, have a helper attempt to start the engine while you wiggle the wiring connectors.
Check also for damage, water, or scorch marks on the panel itself.
Check Ignition Switch
Ignition switches are an important part of the ignition system, bad connections here can cause lots of problems. Ignition switches – send commands to the control module if fitted.
If your mower doesn’t have a control module, then the safety sensors are wired inline to the ignition switch – meaning any sensor that is in the open position will leave the ignition switch with an open circuit (No start). These systems are basic and tend to be the most reliable.
Check this too: Echo Leaf Blower How to and Troubleshooting Guide
Check Ignition Switch
Issues with ignition switches: loose wiring at the switch; corroded terminals; broken terminals; spinning ignition switches.
Wiring specs for ignition systems vary. Check the ignition wiring for damage, corrosion, or loose wires. Have a helper sit on the mower and attempt a start while you wiggle the ignition wires and connectors.
If you have a DVOM:
Check ignition inputs – ground and 12 volt supply.
Switch – Spinning ignition switches cause damage to the wiring and pins.
Corrosion is another common failure. This usually causes unreliable starting and shutdowns.
Wiggle – Try wiggling the wires at the back of the ignition switch while attempting to start the engine, you may need a helper. Often wires simply come loose but do check them for corrosion.
Common Ignition switch problems include:
- Spinning ignition switch
- Loose wiring
- Disconnected wiring
- Corroded wiring terminals
- Corroded / faulty switch
How To Fix a Riding Lawn Mower That Won’t Start
- Work gloves
- Safety goggles
- Wire brush
Check And Charge/Replace Dead Battery
Battery troubles are one of the most common reasons a mower won’t run or click. A corroded battery won’t start an engine, and neither will a drained battery, when you forget to turn off the safety switch. Corrosion can be a usual problem for used riding lawn mower models at cheap prices of $500 below, so make sure to check this when you buy one.
A service monitor on a mower can help you identify when you’ve got battery troubles. But without one, you can check the battery using a multi-meter by following these steps:
- Turn off the ignition system before accessing the battery.
- Set the multimeter to DC voltage
- Use the multi-meter’s red probe to touch the positive terminal and the black probe on the negative terminal.
- If the multitester reads more than twelve (12) volts, the battery is good. Otherwise, it is weak, or dead and you’ve found the problem with your mower.
You can recharge relatively new batteries by:
- Accessing the battery, which is usually under the driver’s seat.
- Connecting the charger clips to the battery terminals.
- Plugging the charger to a power outlet. The charger should work on at least 10volts to charge the battery. Still, a 12-volt charger is sometimes preferred.
- Disconnecting the charger reversing the steps above.
- Plugging the charger to a power outlet. The charger should work on at least 10volts to charge the battery. Still, a 12-volt charger is sometimes preferred.
- Replacing the seat and reconnecting the new battery in your mower correctly.
- If a simple recharge doesn’t work, you need to replace the battery pack in the mower. Avoid a jump start mower to prevent damages to the on-board system
Check The Ignition Switch
The problem with your mower could be with the switches. When you start the engine and your riding mower does not forward nor reverse, your ignition switch’s contacts complete a circuit. This circuit is from a red to a white wire, which is on the B-terminal and S-terminal, respectively.
Check the switch by measuring the resistance between these terminals.
- Red riding
- Pull up the mower’s hood to access the ignition switch.
- Remove its cable harness.
- Remove the tabs to pull the ignition switch out of its slot.
- Turn the key to the start position and set the multi-meter to measure resistance, not voltage.
- Connect the black multi-meter probe to the B prong and the other to the S prong. These terminals are along each other’s diagonal at the bottom of the switch.
- Use the key to turn the ignition switch and start the engine. The resistance should display on the multi-meter when you do this.
The top-rated riding mowers should have good ignition switch measuring 0 ohms. This means its contacts complete the B and S terminal circuit and can send voltage to the solenoid. On the other hand, a damaged ignition switch will measure infinite resistance.
Other common issues you can experience with a damaged ignition switch include loose wiring and connections, corrosion, or spinning ignition. To fix this problem, check the ignition wiring for corroded, damaged, or loose wires
Inspect The Control Module
A control module is a printed circuit with resistors, relays, and a ground side that receive commands from the safety switches. If the sensors in the motor work correctly, a circuit module will also output a command to the starter through the solenoid. However, not every mower has one.
Depending on your model, a control module could be anywhere, even under the seat. And if you notice that your high-quality electric riding mower won’t start and no clicking comes from the device, or cranking doesn’t work, then this module could be faulty.
There are two ways to check the control module yourself:
- Wiggle test: Here, wiggle the red and black wires connected to the control module while you start the mower. If everything checks out fine and the wires are connected, visually check the printed circuit for water damage and loose connections. To save time, you may have someone help you with the wires in a wiggle test while you focus on finding the issue.
- Main fuse check: Modules have internal or external fuses, and a blown fuse cuts out the supply from the battery. First, to check the fuse, remove its zip tie and then pull the fuse from its holder. If any element in the fuse is broken or there’s a fault in the ground connection, you should have it replaced. However, if you’re unsure, you can check for continuity using your multi-meter.
A good fuse should measure near 0 ohms. On the other hand, a blown fuse will measure infinite resistance.
Check Safety Functions
Every mower even the cheapest riding mower you can find in the market has in-built safety features. Typically, sensors or switches control these features, and they are routed through the control module. Once a detector activates a safety function, your mower won’t work as usual.
The main ones to check are the brake pedal switch, blade switch, battery connection, weight sensor (to make sure a driver is sitting before the mower works).
When you jump start the engine, you should press your brake pedal. If the brake pedal doesn’t work, then you need to inspect your brake detector.
- Remove the hood and air-duct screws.
- Pull off the air duct and take the fuel tank and filter out of the way.
- Pull the cable harness off the brake switch, noting the wiring.
- Using the multi-meter probes, touch both prongs that connect to the wiring of the brake detector.
- If the brake switch is okay, the multi-meter should display 0 ohms of resistance. Replace this switch if you read infinite resistance from your multi-meter.
A riding mowers engages when the blade knob is switched off or the transmission isn’t set to park. To check the blade switch, do the following:
- Take out the clutch lever mounting screws. The assembly should drop slightly when the screws aren’t in place.
- Note the prong’s wiring and then disconnect the blade switch’s cable harness.
- Using your multi-meter probes, touch both prongs to measure the resistance of the blade switch.
- Like before, 0 ohms implies your blade switch is good, while infinite resistance means you need to replace it.
Motion detectors, switches, and sensors have in-built override functions. These functions are generally used for tests, and simply disconnecting a detector can cause an override. If you suspect your sensors are on an override, reconnect them before starting the device.
Replace Faulty Solenoid
Follow these steps to change a faulty solenoid:
- First, raise the seat to get to the battery. Then, disconnect the battery terminals, starting with the negative (colored black) and then the red
- Remove the battery from its slot. While at it, check for leaks or corrosion at the bottom and sides. Clean corrosion off the cable leads with a wire brush if they are still there after dusting.
- Disconnect the cable harness that’s connected to the seat’s detector.
- Pull off the battery box after removing its clips or screws.
- Note the wiring connected to the solenoid and then disconnect the cables in any order.
- Remove the mounting and tab both with a screwdriver.
- Remove the faulty solenoid and replace it with the new one.
- Finally, replace the seat, battery, and other parts.
While you can repair some solenoids, it’s often better to change them for longevity. In this way, you can still have the opportunity to place your riding lawn mower on retail in the long run given that the equipment is properly maintained.
Riding mower clatters when starting
If the riding mower makes a a rapid clattering sound when the key is turned to the start position, there is a problem with the battery or a part of the starting circuit.
The clicking noise comes from a part called the starter solenoid. The solenoid connects the battery to the starter motor when the solenoid is energized. The key switch and the safety switches in the starter circuit combine to energize the solenoid. If the solenoid is clicking, the circuit that triggers it is working.
Note: Always disconnect the black negative (-) cable from the battery before making any repair to the electrical system of your tractor.
The most likely causes of the solenoid clicking instead of energizing full are:
- Low battery voltage – Battery needs charging or replacement. Click here for information on charging the battery.
- Loose or corroded connections on cables and wiring that connect the battery to the solenoid and connect the solenoid to the starter. Inspect these connections, remove corrosion and re-establish good electrical contact.
- Loose or corroded connections on the heavy black cables that connect the battery ground circuit to the tractor frame, or damage to the black cable. Inspect these connections, remove corrosion and re-establish good electrical contact.
- Solenoid is not grounded properly to the frame. Check for missing mounting hardware or corrosion that may interfere.
Faulty solenoid. It can click, but not make a complete connection. Replace solenoid with a new one from Online Parts Store
Faulty starter or other mechanical problem with the engine.
If the battery is good, and has a full charge, inspect the heavy cables for loose connections, corroded connections, or visible damage that could be interfering with full current flow. Refer to the Operator’s Manual for additional information about the battery in your particular tractor.
If these do not resolve the issue, professional diagnosis and repairs are needed.
Riding Mower Won’t Start Just Clicks
The most common reason for a clicking sound on a riding mower when you turn the key is a flat battery. Other possible reasons include:
Bad Battery Connections
Bad battery connections are very common, and they prevent power from passing from the battery to the cables because the battery connections are loose, dirty, or damaged.
Battery cables become loose because lawn tractors vibrate a lot, this is why it’s a good idea to service your mower at the start of every season, no matter how well she runs.
Dirty connections are usually caused by the weeping of battery acid at the battery poles. The acid then crystallizes causing high resistance, it looks like a white chalky build-up on the connectors.
To clean the connections, add a couple of spoons of baking soda and a small amount of water, pour this onto the build-up of acid on the connections and battery poles. The soda neutralizes and removes the acid, you’ll need gloves and protective eyewear. After removing the acid, go ahead and remove the connectors and give them a good cleaning with a wire brush or sandpaper.
If you have some petroleum jelly, a small coat will prevent a future build-up.
Connector – Mower blades and engines cause a lot of vibration, bolts come loose from time to time.
Check that both connections, positive (RED + ) and negative (BLACK – ) are clean and tight.
Cables – Check the cables for damage, corrosion, mice find them irresistible.
Flat / Faulty Battery – The fastest way to solve this problem is to jump-start the mower.
Leaking Battery – Check your battery for leaks before attempting to jump-start. If it leaks and it’s a sealed battery, replace it.
However, it’s usually only wet batteries that leak, so best to check your electrolyte level and top up if necessary. As you know acid will burn the skin and eyes, so, you know, gloves, etc.
If the acid build-up is excessive, your battery may be on its last legs, so don’t be surprised if it has failed or does so soon.
But if the leaking is excessive, don’t jump-start, replace it. Batteries are easy to fit, just be sure the battery is the correct size and the poles are in the proper places.
Jump Starting a Riding Lawn Mower
You’ll need jump leads and any 12-volt vehicle. Most cars, trucks, and even Hybrids have a regular 12-volt battery fitted somewhere. Sometimes finding it is the hardest part. If you’re unsure of the voltage, when you find the battery, a sticker on the casing will indicate 12v.
Of course, your battery might just be faulty, jump-starting will probably get you rolling but the problem will still be there. You can test using a voltmeter test tool, which I’ve listed here on the “Small engine repair tools” page.
To jump-start – begin by connecting the positive red (+) of the mower to the red (+) of the car.
Now connect the negative black (-) on the car to a ground (GRD) source on the mower. (Any bare metal will work)
Connect – If you are not familiar with jump-starting, you’ll find a complete guide here, “Jump starting riding mower”. Add the cables in sequence 1, 2, 3, and 4, start the mower, and while idling remove jumper cables in reverse order 4, 3, 2, and 1.
You can check the battery and alternator using a voltmeter. Batteries don’t like sitting idle, they were designed to be charged and discharged continuously. A battery that gets fully discharged will sometimes not come back to life.
Use a voltmeter to check the battery voltage, simply connect red to positive and black to negative.
Test – Check battery voltage using voltmeter – attach a voltmeter to the battery and set it to 20 volts.
If you have a reading above 12.5 volts – go ahead and attempt to start the mower, watch the voltage, a reading below 8 volts is a bad battery and needs to be replaced.
To keep your battery in top condition over winter, you’ll need a battery charger. Use a trickle/smart charger, they’re simple to use, pop on the color-coded crocodile clips, and plug it in, that’s it. Forget it till next spring, then simply turn the key and mow.
Batteries work best and last longer when their state of charge is maintained, off-season charging is always advised.
Charge – Always disconnect the battery before charging. Simply connect red to red, black to black, and plug in the charger. The length of time on charge will depend on how low the battery is and the amp rating of the charger. Usually, 2-3 hours cooking time.
The solenoid is a large relay of sorts. When you turn the key to start your mower, a 12-volt supply from the ignition switch to the solenoid activates it. The solenoid’s job is to connect the battery to the starter motor and crank over the engine for as long as you hold the key.
The click sound is the solenoid trying to work by pulling in the armature; they fail regularly. However, the click sound can also be made for a few other less common reasons and without fully diagnosing, you may find replacing the solenoid doesn’t solve the problem.
if your battery is full and the cables are tight, go ahead and replace the starter solenoid. They’re cheap and easy to fit. And are usually are a universal fit.
Where’s the Solenoid located?
Often just finding the starter solenoid can be challenging. If you don’t find it under the hood, try under the rear wheel, behind the gas tank, or under the seat. The easiest way – follow the red battery cable from the battery. On some engines, the starter and solenoid will be one unit (Kawasaki and Honda engines).
Husqvarna, craftsman-like solenoid is located under the rear wheel fender or under the dash beside the steering column. However, most solenoids will be easy to locate. Fitting is easy, but do disconnect the mower battery first.
Remove – The first step in testing the solenoid – remove the spark plug.
Test – Turn the key, if the clicking sound persists – Go ahead and replace the solenoid.
If on the other hand, the engine cranks over, move on and check for excessive valve lash.
Tight – Check the solenoid terminals; all wiring should be secure and free from corrosion.
Binding Starter Motor
The gear head of the starter motor can bind against the flywheel; this locks the engine and starter motor together. So when you hit the key, all you hear is the click sound.
Testing for this condition involves turning the engine by hand anti-clockwise. Some engines will have a cover over the flywheel, if so, try turning the crankshaft with a ratchet and socket, from the underside of the engine.
If turning the motor anti-clockwise frees it up – you found your problem, the starter motor is binding. Usually, a spray of wd40 on the starter gear head will fix it. If you are lucky, you can get the straw of the WD40 directed at the gear head without removing any covers.
Starters can bind for other reasons – worn bearings, worn gear head, misaligned or loose starter motor.
Binding – Starters can bind against the flywheel. To fix it – spray the starter gear with wd40 and retest. If it continues to bind, replace the gear head or complete the starter motor.
Turning the engine anti-clockwise by hand will unlock it.
Excessive Valve Lash
Engines have valves that open and close in sequence. The inlet valve allows fuel/air mixture in. It then closes and seals the combustion chamber. After the power stroke, the exhaust valve opens and allows spent gases out.
It’s a precise gap between the valve tip and the rocker arm. As the engine wears, this gap gets bigger and will need to be adjusted. The inlet and exhaust valve lash will usually be different specs.
When the valve lash is set correctly – you crank over the engine, the valves open, and release cylinder pressure. This allows the engine to crank over at sufficient speed to create a spark strong enough to start up the engine.
When valve lash is out of spec, the valve is late opening which means pressure in the cylinder is too great for the starter to overcome, that’s when you hear the click sound.
Check out “Valve lash adjusting” it’s for a walk-behind mower, but the process is identical. Adjusting lash isn’t difficult but will require an inexpensive tool called a feeler gauge. You’ll find a link to a good feeler gauge set on the “Small engine repair tools” page.
Test – If you can, place your hands on the flywheel screen – try turning the engine clockwise.
If you’re unable, you likely have excessive valve lash. Lash should be checked every season. Note: Adjusting valve lash requires an inexpensive tool called a feeler gauge.
A carburetor fuel supply usually consists of a fuel bowl, float, and needle. The float is, as its name suggests; a float. Attached to it, is a needle with a rubber tip.
The function of the float is to lift the needle as the fuel level rises in the fuel bowl. When the fuel bowl is full, the needle will be pushed against the fuel feed port, sealing it.
Hydro-locking – Worn carburetor float needle seals have a habit of leaking gas into the cylinder and when the cylinder is full of gas, the piston can’t move, this is known as hydro-locking. Because the piston can’t move, the engine will often make the clicking sound as you try to start the engine.
Removing the spark plug and turning over the engine will release the gas, but the carburetor float valve and the engine oil will need to be replaced.
Other signs that your carburetor needle seal leaks are: overfull oil level; white smoke from the muffler; oil leaking from the muffler; gas dripping from carburetor; a strong smell of gas in the garage.
Fuel Valve Solenoid
Newer model carburetors have a fuel solenoid fitted to the bottom of the fuel bowl, its function is to stop the fuel supply when you shut the engine off. So if you have this newer type of carburetor fitted, it’s not likely you will have a hydro-locking condition.
Leaking Carburetor Valve Seal
Failure commonly occurs in the older type carburetor when the rubber needle seal wears. This results in fuel continuing to fill the carburetor and eventually making its way into the cylinder and crankcase.
Gas in the Oil
If you have gas in the oil, don’t run the engine, the diluted oil offers little protection to internal components. First fix the issue by replacing the carburetor and then change the oil.
Check Oil – Too much oil is a sign that your carburetor needle seal is leaking unless of course, you overfilled the oil yourself.
Needle – The needle wears over time, they turn pink when worn. The fix – replace the seal or the complete carburetor. Using your manual fuel valve will prevent future problems.
Faulty Ignition Switch
A faulty ignition switch can cause all kinds of problems, the click sound can be caused by a bad connection in or at the back of the switch.
Try the Wiggle Test
When turning the key, wiggle the wiring at the back of the ignition switch and see if it makes a difference. It will very often show you where the fault is. Wiring pinouts are specific to each manufacturer.
Wiggle – Try wiggling the wires at the back of the ignition switch while attempting to start the engine, you may need a helper.
Often wires simply come loose but do check them for corrosion.
Faulty Control Module
Control Modules are not fitted to all mowers. The function of the control module is to receive a start request from the ignition switch, and to output a 12 volt supply to the starter solenoid, but only if all safety sensors are in the correct position.
Control Module Test
Control modules do fail and also suffer from loose connectors. Try the wiggle test on the connectors and check for obvious signs of water/corrosion damage. The control module will often live behind the dashboard in a plastic box about the size of a mobile phone.
Wiggle – Like the ignition switch, wires come loose, have a helper attempt to start the engine while you wiggle the wiring connectors.
Check also for damage, water, or scorch marks on the panel itself.
Faulty Starter Motor
A faulty starter can fail electrically, mechanically, or both. Electrically – the copper winding can break; brushes can break or wear out. Mechanically – bearings top and bottom can wear, and the gear head can wear. These issues can cause the starter to bind, so all you hear is the click sound.
Testing the Starter
Checking the starter motor is easy, connect a 12 volt supply direct from the mower battery (+) to the supply wire at the starter. An even easier way is to cross the starter solenoid as per the guide below.
If you find your starter has failed, removing and fitting a new one is simple. The starter motor for Briggs and Stratton offers a good quality starter. Be mindful that B&S has two types of starter – plastic gear head or metal, check before ordering.
Starter – Some starters will have a solenoid and starter motor combined in one unit.
To test, use a jumper lead to bring power from the positive (+) of the battery. to the positive post of the starter. If the engine doesn’t crank – Replace the starter.
Common – Most mowers will have the starter and solenoid separate.
Solenoids are fitted to the body usually under the hood.
Test – Cross a metal screwdriver from one connection to the other, as per the picture.
There will be arcing (sparking) as the screwdriver contacts the poles.
Keep clear of gas and place mower in the park with the parking brake applied and blade off.
If the engine won’t crank over – your starter is faulty, and you should replace it.
Internal Engine Damage
It’s unusual for mower engines to fail completely. They’re generally well-built robust units. Some of these faults can be repaired but most are uneconomic to repair. Total failure doesn’t happen often. But a hard life, low/poor quality oil without doubt increase the chances.
If your riding lawn mower engine clicks when you turn the key but won’t turn over, there’s a pretty good chance your mower could have a bad starter solenoid. Other problems, though not as frequent, include a bad starter motor, a wiring failure, a weak battery or a locked-up engine.
A bad starter solenoid often causes this problem—but not always. The mower could have a bad starter motor, a wiring failure, a weak battery or a locked-up engine.
If you follow these troubleshooting steps, you should be able to get that riding lawn mower engine started so you can get back to mowing.
Supplies you might need
- Work gloves and safety goggles
- Wire brush
- Baking soda and water
- Petroleum jelly
- Clip-on meter probes
Check for a weak battery
First, we’ll check for a weak battery. The click you hear when you turn the key means that the starter solenoid coil is getting power.
The starter solenoid only needs a little current to make the solenoid coil click, but the starter motor needs a lot of current to spin the motor. So a weak battery could have enough current to trip the solenoid coil but not enough current to crank the engine.
To check the battery, use a multimeter to measure the DC voltage across the battery terminals.
- Turn off the ignition.
- Access the battery—in this type of riding lawn mower, you lift the seat to get to the battery.
- With the multimeter set to measure DC voltage, touch the red multimeter probe to the positive or red battery terminal and the black meter probe to the negative or black battery terminal.
- A fully charged battery measures more than 12 volts DC. To provide enough current to spin the starter motor, the battery typically needs to be at least 75 percent charged.
- Charge the battery if it’s weak or dead. The starter motor should spin the engine after you recharge the battery. If not, the next step is the check the cables.
Check the battery cables
If the battery is okay, then corroded or broken wire cables could prevent the starter motor from getting power.
If you find corrosion on the battery terminals and cable ends, here’s how to safely remove it:
- Put on work gloves and safety goggles.
- Disconnect the negative cable and then the positive cable from the battery.
- Use a wire brush to clean the cable ends and battery terminals. If brushing doesn’t remove it all, sprinkle baking soda over the terminals and cable ends and then moisten the baking soda. The baking soda and water will bubble vigorously and dissolve the corrosion. When bubbling stops, use a toothbrush to remove any remaining corrosion.
- Wipe off the terminals and cable ends with a shop rag.
- Using a shop rag, thinly coat the battery terminals with petroleum jelly to help prevent corrosion.
Testing the cables.
If you found no corrosion, or if the motor still won’t start after you remove corrosion, check if the red battery cable is delivering power to the solenoid post by measuring voltage on the red terminal post.
With the multimeter set to measure DC voltage, touch the red meter probe to the red post on the starter solenoid and the black meter probe to the negative terminal on the battery. It should measure more than 12 volts. If it doesn’t, replace the red battery cable.
Note: Don’t let the meter lead touch both the solenoid posts at the same time or you’ll see a severe spark.
If the motor still doesn’t turn over with a good red cable, the solenoid is next on the list of likely suspects.
Test the starter solenoid
Check the starter solenoid by measuring voltage on the black post at the same time as the solenoid clicks.
You’ll need some clip-on meter probes to hold the probes on the wires as you turn the ignition key, unless you have a helper to turn the key while you hold the probes on the wires.
- Disconnect the black starter cable from the solenoid post and attach the red meter probe to the post.
- Clip the black meter probe to the negative battery terminal.
- Hold the ignition key in the start position—you should hear the solenoid coil click.
- Check the voltage reading and then turn the key to the off position.
If the solenoid coil clicks, the multimeter measured more than 12 volts if the black post gets power. If it measures no voltage when the solenoid coil clicks, replace the starter solenoid.
Test the starter cable
If the multimeter measured more than 12 volts on the black solenoid post after the solenoid clicked, you know that the starter solenoid works. Now we’ll check the starter cable that connects the solenoid to the starter.
To check the starter cable, we’ll use a voltage drop test to measure resistance through the starter cable. Using a voltage drop test is more accurate than a simple resistance test for a large cable with many copper strands, because a simple resistance check simply detects any current; it can’t detect whether the cable can carry enough current to spin the starter motor.
Voltage is measured from the solenoid post to the starter motor stud. Ideally, you should measure less than 1 volt during this test, indicating voltage is nearly the same at the solenoid post and the starter motor stud. If it’s more than 1 volt, it means wire strands inside the cable are broken.
- To start the test, reconnect the black starter cable to the solenoid post and clip the red meter probe to the black post.
- Lift the mower hood and disconnect the spark plug wire so the engine has no chance of starting.
- Clip the black meter lead to the starter motor stud that connects the black cable to the starter.
- Hold the ignition key in the start position and check the voltage reading after the click. Turn the key to the off position after checking the voltage.
- If you measure a drop of more than 1 volt through the starter cable, replace the starter cable.
- Check for a seized engine.
- If the starter cable is okay, you know that the starter motor is getting power.
To see if the engine spins, remove the plug from the screen above the flywheel to access the flywheel bolt. Use a socket wrench to rotate the flywheel bolt clockwise and try to spin the engine. If the engine won’t spin because it’s locked up, have a service technician diagnose and repair the problem.
If you can spin the engine, replace the starter motor because it’s not spinning the engine when activated.
Lawn Mower Clicks But Won’t Start or Turn Over
A lawn mower clicks but won’t start or turn over when the battery cables, terminals and wiring are loose or corroded; there is a bad ground; the battery is weak; the starter solenoid is bad; the charging system is faulty; or the starter motor is bad.
When working on your mower’s electrical system, follow safety precautions outlined in your operator’s manual. This includes wearing gloves and eye protection.
Note: Always disconnect the negative cable (black) from the battery before making any repairs to the electrical system.
Below are the main causes of the issue;
Damaged or Loose Battery Cables & Wiring & Terminals on the Lawn Mower
Check the cables and wiring from the battery to the solenoid and from the solenoid to the starter. Ensure they are in good condition and making good connections. Inspect the terminals to make sure they are free of corrosion and securely attached. These items need to have excellent conductivity and connections.
Solution: Remove any corrosion found on the wires. If you find that the cables keep coming loose or they are broke, they must be replaced. Bad cables can contribute to a bad battery and starting issues.
Remove any corrosion on the terminals. Disconnect the battery from the mower and clean them. A wire brush and a baking soda mix consisting of 2 cups of water and 3 heaping tablespoons of baking soda works well. Repair or replace any wiring that has signs of corrosion.
Add a dielectric grease to protect terminals and wiring from corrosion. Replace terminals when they are in damaged or in bad condition.
Bad Ground on the Lawn Mower
Check the black cable from the battery to the frame of the lawn mower. Check the ground from the solenoid. (A 3-post solenoid is self-grounded). Remove any corrosion you find and make sure it’s making good contact.
Solution: Replace a damaged cable coming from the battery to the frame. Remove any corrosion found for the grounds from the battery and the starter solenoid.
Bad or Weak Battery on the Lawn Mower
A weak battery or one that won’t hold a charge won’t provide enough power for your lawn mower to start. It will just click and not turn over or start.
Check the voltage of a lawn mower battery
Use a multimeter’s red and black prongs and touch them to the corresponding colors of terminals on the lawn mower battery. The most common type of riding lawn mower and zero turn lawn mower batteries have a voltage of 12 volts.
You may get a voltage reading between 11.5 and 12.7. A reading of 11.5V indicates a battery that is almost dead while a 12.7V reading indicates a fully charged battery.
Charge a lawn mower battery
- Put on your safety gear so your eyes and skin are protected from acid or electrical shock.
- Get access to the battery and its terminals. You may need the screwdriver to uncover the lawn mower’s body to get access to the battery or battery casing.
- Leave the battery in its casing with the terminal cables attached.
- Connect the charging cables starting with the red cable first (The one with the positive sign on it)
- The red cable clamp goes onto the positive terminal, and the black cable clamp goes on the negative battery terminal.
- Make sure that your skin only touches the rubber coating of the charging cables and clamps to.
- Set the charger’s voltage level and amp level to the desired level. The average volt level for lawn mowers is usually 12 volts. More amperage charges the battery faster (Start with two amps and work up to no more than 10 amps).
- If your charger has a battery charging gauge, keep the charger connected until the battery is fully charged.
Solution: When the battery is weak, use a battery charger to charge it. If you find the battery will no longer holds a charge, it’s time to replace it with a new one.
A battery that dies and is able to be charged may indicate you have a problem with the mower’s charging system. See information about the charging system below.
Bad Starter Solenoid on the Lawn Mower
When your mower keeps clicking, a likely cause is a bad lawn mower starter solenoid. The solenoid acts like a on-off switch. It is an electromagnet switch that is actuated to engage the starter motor so the engine will turn over.
Most starter solenoids are mounted on the starter. However, they do not have to be to still work. Follow the positive wire from the battery to find the solenoid.
There are many reasons why a starter solenoid can go bad. The internal spring can become weak or the copper plate can start to corrode. A bad ground, weak starter or bad battery can also result in the starter solenoid failing.
Solution: Test your starter solenoid. You’ll need a volt-ohms meter, screwdriver, continuity light and some wrenches. Follow the instructions found in “How to Tell Your Lawn Mower Solenoid is Bad“. If you are able to start your mower by bypassing the solenoid, it must be replaced.
Bad Starter Motor on the Lawn Mower
If you’ve check the battery, cables, wiring, ground and starter solenoid only to find them in good condition, but still have a starting problem, your starter may be the problem. The starter can be removed and tested.
A starter can be a pricey item on a lawn mower. Have your local dealership confirm whether you have a starter motor problem. You can also bring the starter to a local repair shop that specializes in starter and alternator repairs. The personnel at the repair shop can test the starter and often times rebuild it if necessary.
Bad Lawn Mower Charging System Drains the Battery
A bad charging system will not keep your battery charged and in turn cause a weak battery to not start your mower. Depending on the size of your lawn mower, it may have an external alternator like one you find on a car. It may also have an internal one located under the flywheel. Most lawn mowers will have an internal alternator.
Perform the steps provided here to check the charging system using a volt-ohms meter.
If you find your lawn mower is no longer charging the battery, hire a mechanic familiar with your charging system perform further tests and necessary repairs. Troubleshooting the exact cause of a charging system can be quite difficult.
If you’re not familiar with the charging system, you will probably just end up throwing parts at your mower. This can get very expensive especially since, if you get it wrong, you can’t return an electrical part. You could be looking at a bad stator/alternator, regulator or other electrical problem.
Lawn mower turning over but not starting
This problem is commonly related to either the air, fuel, or spark supply systems within the motor. The internal combustion engine will need all three of these elements to run, so if one of them is not sufficient you may see your lawn mower turning over but not starting.
Potential Causes include;
Bad Spark Plug
If your mower isn’t getting enough of a spark for the ignition to take place, it may cause this problem. Take out the spark plug and check the spark element is intact and clean. A bad spark plug is an easy fix.
Spark Plug Wire Not Connected
While checking your plug, ensure that the spark plug wire is making good contact with the end of the spark plug. Ensure that the rubber cover is securely over the spark plug.
Dirty Air Filter
An air filter that’s not letting enough air into the motor can inhibit combustion. Locate the air filter on your mower and remove the plastic cover. If the filter is covered in dirt, grass, or some other contaminant, this may be the reason for your lawn mower turning over but not starting. The engine needs to be provided with enough air for the combustion process to work.
Fuel System Not Working
There are a few components in the fuel system that could be causing the problem. If gas has been left in the mower without running for an extended period, it may have gummed up the carburetor. You can also check the fuel filter, and if it is full of debris, or the clear container around the fuel filter is completely dirty, this could be contributing to the problem. To test the fuel system, you must rule out the other two parts of the equation. If the air filter is clean and the spark plug is fully intact, try spraying some starter fluid directly into the chamber with the air filter off the mower. If the mower starts with this method, or starts and then stalls, that tells you that it is a problem with the fuel delivery to the motor.
Malfunctioning Safety Switch
Usually, if a safety switch such as the seat or emergency brake is not making contact, the mower will not even turn over. There is, however, a small chance that a switch may be working intermittently if it is dirty, or the contacts are not able to meet properly. This may cause your riding mower to turn over but not start. It is worthwhile to check the safety switches if the above fixes have not worked for you.
Check that the seat switch is working by re-distributing your weight over different parts of the seat and trying to start the mower. If all else is in working order and it still wont start, the switch under your seat may be bad.
Next, check that the emergency brake switch is making contact, if it is faulty, it will prevent the mower from starting even when the emergency brake is engaged. These causes are uncommon but may possibly be your cause if everything else is working properly.
How to Fix a Mower That Turns Over But Doesn’t Start
Follow these steps to fix common issues that cause a lawn mower not to start;
How to Fix a Bad Spark Plug
If you have checked and determined you have a bad spark plug that may be the cause of your problem, you will need to either clean or replace the plug. Figure out which option is right for your mower by checking out the condition of the electrode, the ceramic coating, and the terminal that contacts the wire.
If the coating is cracked or the electrode is burnt, shortened, or missing, this will likely be the cause of your problem. You will want to replace the plug. If you find that the spark plug is just dirty on the tip, preventing a proper spark or connection with the wire, you may be able to clean it with a small brush and a light solvent.
How to Fix a Spark Plug Wire Not Connected
If you find that the wire which connects your spark plug to the starting mechanism is not making contact, that could also be causing your problem. To fix this, you may only have to push the rubber shroud down around the plug so that it’s tighter.
You can look inside the shroud and check that the wire is showing and has enough exposed to make contact. If the rubber shroud is ripped or worn out, you may need to replace the spark plug wire or shroud.
How to Fix a Dirty Air Filter
If you have checked your air filter and discovered that it is covered with sand, dirt, grass, leaves or anything of the sort, you will need to blow it out for it to start working properly. Try tapping the air filter on a solid surface upside-down to get the large debris off.
If you have an air compressor, stick the nozzle inside the filter and blow out. This will release a lot of the fine particulates trapped in the filter. If neither method solves the problem, it may be time for a new air filter.
How to Fix a Fuel System That’s Not Working
If you have discovered a very dirty fuel filter, you may be able to replace this easily by yourself. You will have to find the right part for your mower and acquire it. The fuel filter is easily changed by releasing the clamps at both sides and connecting the new one the same way. Use a bucket to catch any fuel that runs out of the lines when disconnected.
If the fuel filter is fine and you have ruled out any other parts of the ignition system, the carburetor may be the place to look next. Your carb may be gummed up, especially if the mower hasn’t been run in a while. If you suspect this is the case, you can either replace the carburetor or try and clean it.
Cleaning a carburetor is an in-depth process and deciding whether to do this or leave it to a pro depends on how ambitious you are. If you decide to take it apart, make sure and take a picture or draw a diagram to remember where every part goes.
How to maintain a Riding Lawn Mower
Follow these steps to maintain your lawn mower;
Change the lawn mower carburetor filter.
Your lawn mower’s air filter guards the carburetor and engine from debris like grass clippings and dirt. When the air filter becomes clogged or too dirty, it can prevent the engine from starting. To keep this from happening, replace paper filters—or clean or replace foam filters—after every 25 hours of engine use.
The process for removing the filter depends on whether you are operating a riding or walk-behind lawn mower. For a riding mower, turn off the engine and engage the parking brake; for a walk-behind mower, pull the spark plug wire from the plug. Then, lift the filter from its housing.
The only choice for paper filters is replacement. If you’re cleaning a foam filter, wash it in a solution of hot water and detergent to loosen grime. Allow it to dry completely, and then wipe fresh motor oil over the filter, replace it in its housing, and power up the mower—this time to the pleasant whirring of an engine in tip-top condition.
Check the spark plug.
The spark plug is responsible for creating the spark that ignites the fuel in the engine. If it’s loosened, disconnected, or coated in water or carbon residue, the spark plug may be the cause of your machine’s malfunction.
Locate the spark plug, often found on the front of the mower, and disconnect the spark plug wire, revealing the plug beneath. Use a socket wrench to unscrew the spark plug and remove it.
Check the electrode and insulator. If you see buildup, spray brake cleaner onto the plug, and let it soak for several minutes before wiping it with a clean cloth. Reinstall the spark plug, first by hand, and then with a socket wrench for a final tightening. If the problem persists, consider changing the spark plug.
Clear the mower deck of debris.
The mower’s deck prevents grass clippings from showering into the air like confetti, but it also creates a place for them to collect. Grass clippings can clog the mower deck, especially while mowing a wet lawn, preventing the blade from turning.
If the starter rope seems stuck or is difficult to pull, then it’s probably due to a clogged deck. With the mower safely turned off, tip it over onto its side and examine the underbelly. If there are large clumps of cut grass caught between the blade and deck, use a trowel to scrape these clippings free. When the deck is clean again, set the mower back on its feet and start it up.
Clear the vent in the lawn mower fuel cap.
The mower started just fine, you’ve made the first few passes, then all of a sudden the mower quits. You pull the cord a few times, but the engine just sputters and dies. What’s happening? It could have something to do with the fuel cap. Most mowers have a vented fuel cap. This vent is intended to release pressure, allowing fuel to flow from the tank to the carburetor. Without the vent, the gas fumes inside the tank begin to build up, creating a vacuum that eventually becomes so strong that it stops the flow of fuel.
To find out if this is the problem, remove the gas cap to break the vacuum, then reattach it. The mower should start right up. But if the lawn mower won’t stay running and cuts off again after 10 minutes or so, you’ll need to get a new gas cap.
Clean and refill the lawn mower fuel tank.
An obvious—and often overlooked—reason your mower may not be starting is that the tank is empty or contains gas that is either old or contaminated with excess moisture and dirt. If your gas is more than a month old, use an oil siphon pump to drain it from the tank.
Note: spilled oil can cause smoking, but there are other reasons this might happen.
Add fuel stabilizer to the tank.
Fill the tank with fresh fuel and a fuel stabilizer to extend the life of the gas and prevent future buildup. A clogged fuel filter is another possible reason for a lawn mower not to start. When the filter is clogged, the engine can’t access the gas that makes the system go. If your mower has a fuel filter (not all do), check to make sure it’s functioning properly.
First, remove the fuel line at the carburetor. Gas should flow out. If it doesn’t, confirm that the fuel shutoff valve isn’t accidentally closed. Then remove the fuel line that’s ahead of the fuel filter inlet. If gas runs out freely, there’s a problem with the fuel filter. Consult your owner’s manual for instructions on replacing the filter and reassembling the mower.
Inspect the safety release mechanism cable.
Your lawn mower’s reluctance to start may have nothing to do with the engine at all but rather with one of the mower’s safety features: the dead man’s control. This colorfully named safety bar must be held in place by the operator for the engine to start or run. When the bar is released, the engine stops. While this mechanism cuts down on the likelihood of horrific lawn mower accidents, it also can be the reason the mower won’t start.
The safety bar of a dead man’s control is attached to a metal cable that connects to the engine’s ignition coil, which is responsible for sending current to the spark plug. If your lawn mower’s engine won’t start, check to see if that cable is damaged or broken. If it is, you’ll need to replace it before the mower will start.
Fortunately, replacing a broken control cable is an easy job. You may, however, have to wait a few days to get the part. Jot down the serial number of your lawn mower, then head to the manufacturer’s website to order a new cable.
Check to see if the flywheel brake is fully engaged.
The flywheel helps to make the engine work smoothly through inertia. When it isn’t working properly, it will prevent the mower’s engine from working. If it is fully engaged, it can make a mower’s pull cord hard to pull. Check the brake pad to see if it makes full contact with the flywheel and that there isn’t anything jamming the blade so the control lever can move freely.
If the flywheel brake’s key sheared, the mower may have run over something that got tangled in the blade. It is possible to replace a flywheel key, but it does require taking apart the mower.
Look out for signs that the mower needs professional repairs.
While repairing lawn mowers can be a DIY job, there are times when it can be best to ask a professional to help repair a lawn mower. If you’ve done all of the proper mower maintenance that is recommended by the manufacturer, and gone through all of the possible ways to fix the mower from the steps above, then it may be best to call a pro. Here are a few signs that indicate when a pro’s help is a good idea.
You see black smoke. The engine will benefit from a technician’s evaluation, as it could be cracked or something else might be worn out.
Excessive oil or gas usage. If you’ve changed the spark plugs, and done all of the other maintenance tasks, and the mower is consuming more than its usual amount of oil or gas, consult a professional for an evaluation.
The lawn mower is making a knocking sound. When a lawn mower starts making a knocking sound, something could be bent or out of alignment. It may be tough to figure this out on your own, so a pro could help.
A vibrating or shaking lawn mower can be a sign of a problem beyond a DIY fix. Usually something is loose or not aligning properly.
How to troubleshoot riding lawn mower to remedy engine problems
- Unscrew the air filter cover from the side of the lawn mower engine with the screwdriver. Pull out the old dirty air filter and replace it with a new one and tighten the cover back on.
- Pull the spark plug cap off of the spark plug on the front of the engine. Fit the proper sized socket on the spark plug and unscrew it with the socket wrench. Finger tighten the new spark plug. Then place the socket on the foot-pound torque wrench and tighten the spark plug..
- Follow the fuel line under the gas tank to the side of the carburetor. Locate the screw under the carburetor holding on the fuel bowl. The fuel bowl can get gummed up with old gas and prevent the gas from entering the piston.
- Unscrew the fuel bowl with the screwdriver. Pull it off and dump out any old gas in it. Spray carb cleaner into the bowl and onto the float and valve area above the fuel bowl. Screw the fuel bowl back on tightly.
Mower only starts when I jump solenoid
This means the solenoid is lacking power from the start of the ignition switch, generally this can be a broken wire or bad ignition switch, the fact that it starts and runs indicates still having ignition power to the engine. Next check the seat switch and the brake switch, if both are good and making correct contact then move on to the ignition switch start wire going to the starter solenoid and then the actual ignition switch itself.
What Keeps Draining My Lawn Mower Battery?
Your lawn mower battery could be draining from a number of causes such as loose, dirty, or corroded battery cables, electronic drain, or a bad battery. There could also be a faulty charging system, a failing voltage regulator, or other issues that are draining your lawn mower battery.
Possible Reasons include;
Dirty or Corroded Battery Cables
It happens to your automobiles, and it can certainly happen to your lawn mower battery. You open up the hood, there on the battery cables is a whitish, powdery crust building up around the terminals.
Hydrogen gas escapes from your battery and it reacts with the metal on the battery posts and cables causing corrosion. If it gets too bad it will prevent the battery from recharging or sending power to the mower altogether. It’s annoying, but a simple fix.
How to Fix: Put on your safety gear, chemical-resistant gloves, eye protection, all that stuff. There could be some battery acid, or the corrosion could be irritating to skin and mess up clothing. Disconnect the battery terminals, pour baking soda (you can also use battery cleaner from your local auto parts store) around the corroded areas, and then pour a little bit of water on the baking soda to neutralize the corrosion and battery acid. If the corrosion is stuck on, you can use a small wire brush to scrape it off, then use more baking soda and water to dissolve the residual corrosion. Use paper towels next to clean and dry the areas then reattach the cables, charge your battery again, and you’re good to ‘mow’.
Loose Battery Cables
If you have a loose connection, then of course the battery is going to struggle to keep everything running correctly. The constant vibrations of the motor over time can cause the bolts to loosen slightly causing your battery to work overtime to power your lawn mower.
How to Fix: Simply wiggle all the cable connections to see if they are loose. If any need tightening, clamp them down properly then get back to tending your yard.
A Bad Alternator
The alternator helps to keep the electrical system running and recharges the battery while the engine is running. If the alternator is failing, then it means the battery has to take up the slack and it’s not getting enough charge to keep it in tip-top shape.
How to Check: To check the alternator, turn the mower’s lights on, leave them on then turn off the mower. If the alternator is good, then the lights will dim when the motor stops. If the lights remain the same intensity, then it means the battery is carrying the load and the alternator needs to be replaced. Once that is fixed, the battery will be recharged every time you run your mower.
The Voltage Regulator is Going Bad
If the voltage regulator is going bad, it will cause the battery to drain pretty quickly.
How to Check: You will need your trusty multimeter to check for this problem. Set it to check the voltage, turn on the mower just enough to get a load running through the electrical system. Check the battery terminals with the multimeter. You are looking for voltage between 13.8 and 14.5 volts. Below 13.8 means your battery is failing or is not sufficiently charged, and above 14.5 means you have a fault in the voltage regulator, and it needs to be replaced.
The Battery Needs Maintenance
Another reason your battery is not able to keep a charge is that your battery needs some maintenance. Lawn mower and car batteries are known as wet cell batteries. There is sulfuric acid inside the battery cells and over time gasses escape, the liquid is reduced, resulting in a poor performing battery.
How to Fix: You can check this by first donning your protective gear. Gloves, safety glasses, you know the drill. Next, carefully pop off the plastic covers to the battery and peer inside. If the liquid is lower than the round ports, it needs water. Use a small funnel and pour distilled water into the ports to raise the liquid level only to the bottom of the ports. You don’t want to overfill these holes. Put the covers back when you’re done, give the battery a good charge and you should be set. Now is also a good time to check for dirt and corrosion at the battery terminals.
Along with other issues that can occur from not pushing the throttle to the top, it can drain your battery. If the motor is not running at full RPMs, the battery may not be getting a full charge. So go ahead, crank that throttle up and run your mower full blast. It was built to run full throttle.
Your Battery is Failing
Another reason your lawn mower battery keeps draining could be because it has reached the end of its life cycle and it is dying. Mower batteries typically have a lifespan between 3 to 5 years with proper care. Of course, you can get the occasional lemon that doesn’t even tick on that long, but if you can’t find anything else that keeps draining your battery, you might have to think about replacing your old one. The simple fix here is to buy another lawn mower battery.
With all the new advances on everything electronic, your battery could be experiencing a parasitic electronic drain. This happens when the lawn mower is turned off, but a tiny electrical charge is still sucking minute doses of power. Given time, this could weaken or completely drain the battery. This can be difficult to check for and to fix, but if all other avenues have been exhausted, you may have to check for this. You will need a multimeter for this particular diagnosis.
How to Check: Set your multimeter to ammeter mode then set the probes on the battery posts when the mower is turned completely off. If you get a reading of more than 1mA, then your electrical system is still drawing current off the battery via a relay system, or a component in the mower that has a standby mode.
To remedy the parasitic drain, you may have to take it in to get your mower serviced. You could also disconnect the battery each time to save it from the power-sucking culprit or keep a maintenance charger on the battery when not in use.