Riding Mowers & Tractors: Won't start

There are numerous explanations for why a riding lawn mower won't start, including everything from bad gas or a bad battery to a failed starter motor or bad ignition coil.

If you find yourself constantly having to charge the battery before starting the engine, a bad battery or failed alternator could be causing the problem. Connect the battery to a charger and if the battery won't charge fully within 8 hours, then you'll likely need to replace the battery. If the battery is okay, then a problem in the engine's charging system is causing the constantly drained battery. The engine uses an alternator to generate current, which constantly charges the battery and powers the mower's electrical system while the engine runs. When the alternator fails, the battery attempts to power the mower on its own and quickly drains without recharging.

If the engine spins but won't start when you turn the ignition key, the engine is missing one of its key ingredients for starting-fuel, compression or spark. Check your basics first, then watch our riding mower engine spins but won't start video for troubleshooting tips to get the engine started.

You may hear a click when you turn the ignition key but nothing else. A dead battery, bad starter solenoid, failed starter motor or a seized engine could be the cause. Our riding mower engine clicks but doesn't turn over video will help you figure out what to fix.

When the mower seems completely dead, you'll need to check the battery, ignition switch, interlock switches, starter solenoid and wiring to find out what's wrong. Our riding lawn mower engine won't turn over or click video will help you systematically check those parts.

riding mowers & tractors

These repairs may help solve your riding mowers & tractors problem

Replace the riding mower ignition switch

Replace the riding mower ignition switch

The ignition switch in a lawn tractor or riding mower supplies power to the electrical components of the engine. If the lawn tractor doesn't turn over when you turn the key to the On position or doesn't shut off when you turn the key to the Off position, you might need to replace the ignition switch.

February 1, 2015
By Lyle Weischwill
How to replace a riding lawn mower ignition switch

If your riding lawn mower won't start when you turn the key to on (or won't stop when you turn it to off) the ignition switch might be broken. This DIY repair guide and video show how to replace the ignition switch on a riding lawn mower in 4 quick steps.

Repair difficulty
Time required
 15 minutes or less
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Replace the riding mower ignition coil

Replace the riding mower ignition coil

The ignition coil in a riding mower or lawn tractor produces the energy to cause the spark at the spark plug. The ignition coil is the likely the cause when the engine won't spark if, after you remove the kill wire, there's no spark from a known good spark plug.

January 1, 2015
By Lyle Weischwill
How to replace a riding lawn mower ignition coil

If your riding lawn mower doesn’t get spark from a good spark plug, the problem could be the ignition coil. This repair guide and video explain how to replace an ignition coil on a riding lawn mower in 30 minutes.

Repair difficulty
Time required
 30 minutes or less
Read more
Replace the riding mower carburetor assembly

Replace the riding mower carburetor assembly

The carburetor mixes gas with air before the fuel goes into the cylinder. If the gas/air mix isn't balanced, the engine won't start or the engine will run rough and stall when you try to drive the riding mower. A damaged carburetor may also leak gas. Replace the carburetor if it causes any of these symptoms.

January 1, 2015
By Lyle Weischwill
How to replace a riding lawn mower carburetor

When a lawn tractor engine surges or is hard to start, the problem could be a clogged or damaged carburetor. This DIY repair guide and video show how you can replace the carburetor yourself.

Repair difficulty
Time required
 45 minutes or less
Read more
Rebuild the riding mower engine carburetor

Rebuild the riding mower engine carburetor

The carburetor mixes fuel with air to create a combustible mixture that enters the engine cylinder and ignites to drive the piston. Impurities in gasoline can clog the carburetor, preventing the engine from starting. Carburetor clogs can also cause the engine to run rough and the engine may stall when you try to drive the riding mower. Seals and gaskets in the carburetor eventually wear out and can leak gas. Use a carburetor rebuild kit to refurbish a clogged or leaking carburetor.

January 1, 2015
By Lyle Weischwill
How to rebuild a riding lawn mower carburetor

Does your riding lawn mower engine run rough or misfire? The carburetor might be clogged or worn. This DIY repair guide and video show how to rebuild the carburetor in a riding lawn mower in about an hour.

Repair difficulty
Time required
 60 minutes or less
Read more
Replace the riding mower battery

Replace the riding mower battery

If the riding mower or lawn tractor engine doesn't make any noise when you try to start the mower, it might be time to replace the lawn tractor battery. A good indicator that the lawn tractor needs a new battery is if you charge the battery, and it loses the charge quickly.

Replace the riding mower alternator

Replace the riding mower alternator

The alternator attaches to the engine under the flywheel and generates power for the tractor while the engine is running. The alternator also recharges the battery while the engine runs. If the engine won't start because the battery drains while running the tractor, the alternator could be at fault. Check DC voltage at the battery with the engine running. You should measure between 13 and 14 volts. If not, then you may need to replace the alternator.

Replace the riding mower starter solenoid

Replace the riding mower starter solenoid

The starter solenoid is a coil-activated switch that activates the starter motor. When you turn the ignition key to the start position, the starter solenoid sends current to the starter motor. You'll hear the solenoid click when the ignition switch activates the solenoid. Replace the solenoid if it doesn't click when it gets power from the ignition switch. You'll also need to replace the solenoid if it clicks but doesn't send current to the starter motor to spin the engine.

How to replace the starter solenoid on a riding lawn mower

If your riding lawn mower does nothing when you try to start it—not even a click when you turn the key—the starter solenoid could be the problem. This step-by-step repair guide and video explain how to replace a riding mower starter solenoid in 30 minutes or less.

Repair difficulty
Time required
 30 minutes or less
Read more
Replace the riding mower air filter

Replace the riding mower air filter

The air filter traps debris from air entering the carburetor. A dirty air filter could be the problem if the engine stalls after starting or the engine runs rough or sputters. The carburetor won't get enough air to mix with the fuel for combustion if the air filter is dirty. Inspect the air filter regularly and replace it when dirty.

How to replace the air filter on a riding lawn mower

If your riding lawn mower runs rough or stalls after starting, the air filter could be dirty. This DIY repair guide and video show how to replace a clogged riding mower air filter in less than 15 minutes.

Repair difficulty
Time required
 15 minutes or less
Read more
Replace the riding mower starter motor

Replace the riding mower starter motor

The starter motor spins the flywheel to start the engine when you turn the ignition key to the start position. If the starter motor runs but doesn't spin the flywheel, check the starter motor's drive gear for damage. A defective drive gear won't mesh with the flywheel teeth to spin the engine. Replace the starter motor if you find damage to the drive gear. The starter motor may be defective if it doesn't run when activated. Other failures such as a locked-up engine or poor current flow to the motor can prevent the starter from spinning, so check those issues first. Replace the starter motor if it won't run and you've eliminated other possible failures that could prevent the starter motor from running.

How to replace the starter motor on a riding lawn mower

If your riding lawn mower won’t start, but you hear a click when you turn the key, the starter motor is probably the problem. You can install a replacement starter motor yourself, using the steps in this repair guide and video.

Repair difficulty
Time required
 30 minutes or less
Read more
Replace the riding mower brake interlock switch

Replace the riding mower brake interlock switch

The brake interlock switch detects whether you have the brake pedal fully pushed down. The parking brake holds the brake pedal in the fully depressed position so the brake interlock switch also recognizes whether you have the parking brake set. The brake interlock switch prevents you from starting the tractor without the brake pushed in or the parking brake set. Replace the brake interlock switch if the engine won't start because the brake interlock switch doesn't detect the brake pedal fully depressed or the parking brake set.

How to replace the brake interlock switch on a riding lawn mower

The brake interlock switch is a safety device that won't let a riding lawn mower start if the brake isn't on. If the switch breaks, you can't start the engine even when your foot is on the break or the break is set. This repair guide and video show how to install a new riding mower brake interlock switch in about 30 minutes.

Repair difficulty
Time required
 30 minutes or less
Read more
Replace the riding mower engine fuel filter

Replace the riding mower engine fuel filter

The engine fuel filter screens impurities from the gasoline going to the carburetor. A clogged fuel filter won't allow gas to flow to the carburetor so the engine won't start. A damaged filter won't screen impurities from the gasoline, resulting in a clogged carburetor. Replace the engine fuel filter if it's damaged or clogged.

January 1, 2015
By Lyle Weischwill
How to replace a riding lawn mower fuel filter

If your riding lawn mower’s engine runs rough or won't run, the fuel filter could be dirty. This repair guide and video show how to easily replace the fuel filter on your riding lawn mower in 15 minutes.

Repair difficulty
Time required
 15 minutes or less
Read more
Symptoms common to all riding mowers & tractors

Choose a symptom to see related riding mower and lawn tractor repairs.

Main causes: dead battery, stale fuel, bad starter solenoid, ignition system problem, bad ignition interlock switch, clogged carburetor
Main causes: punctured tire or inner tube, leaky valve stem, damaged wheel rim
Main causes: damaged tie rods, bent or worn wheel spindle, worn front axle, damaged sector gear assembly
Main causes: faulty battery, bad alternator
Main causes: engine overfilled with oil, leaky head gasket or sump gasket, damaged carburetor seals, cracked fuel pump, broken fuel line
Main causes: damaged cutting blade, worn deck pulley, damaged mandrel pulley, loose fasteners on mower deck components
Main causes: worn or broken ground drive belt, bad seat switch, transaxle freewheel control engaged, transaxle failure, dirty carburetor
Main causes: shift lever needs adjustment, neutral control needs adjustment
Main causes: unlevel mower deck, dull or damaged cutting blades, worn mandrel pulleys, bent mower deck, engine needs tune up
Repair guides common to all riding mowers & tractors

These step-by-step repair guides will help you safely fix what’s broken on your riding mower or lawn tractor.

How to replace a mandrel assembly on a riding lawn mower

Replace the mandrel assembly if the blade shaft vibrates or doesn't spin.

Repair difficulty
Time required
 30 minutes or less
How to replace the air filter on a riding lawn mower

Get your mower running smoothly again by replacing the air filter—it's a quick job you can do yourself, following these steps.

Repair difficulty
Time required
 15 minutes or less
February 1, 2015
By Lyle Weischwill
How to replace a riding lawn mower ignition switch

Get your mower started again by replacing the ignition switch—it's a quick job you can do by following these steps.

Repair difficulty
Time required
 15 minutes or less
Articles and videos common to all riding mowers & tractors

Use the advice and tips in these articles and videos to get the most out of your riding mower or lawn tractor.

May 1, 2017
Troubleshooting a riding lawn mower blown fuse video
By Sears PartsDirect staff

Test the ignition switch and wire harnesses to find the short.

June 1, 2016
How to mow a lawn for healthier grass
By Erin Hynes

How often and tall you mow your lawn has a big impact on its health. Check out these 3 rules.

March 1, 2016
How to level a riding lawn mower deck for an even cut video
By Sears PartsDirect staff

Mower not cutting the grass evenly? Your mower deck might be the problem.