Riding Mower and Tractor: Won't start

If your riding lawn mower or lawn tractor doesn't start and doesn't make a clicking noise when you turn the key, first check that the battery is charged. If the battery is fully charged, the starter solenoid could be broken or the ignition system may not be activating the solenoid.

If the starter solenoid clicks but the starter motor doesn't run, the solenoid could be defective.

If the engine cranks when you turn the key but doesn't start, make sure the tractor has fresh fuel. Gas collects water over time and then doesn't ignite well.

If the gas is fresh, the problem could be a dirty carburetor. Carefully squirt a short burst of starting fluid through the carburetor air intake and then try to start the engine. If the engine starts and runs briefly, it means the ignition system and cylinder compression both are good. In that case, concentrate your troubleshooting on the fuel system. Clean or replace the air filter to ensure the carburetor is getting enough air. Clean or replace the carburetor if it's gummed up with deposits.

If the engine doesn't start with the starter fluid test, check the spark plug for fuel, oil or carbon deposits. If the spark plug is okay, check the flywheel key, especially if you just hit a rock or stump and the engine suddenly stopped. A broken flywheel key keeps the engine from starting.

If the flywheel key is okay, use a compression gauge to check cylinder compression. If you don't detect cylinder compression, you might need to adjust valve lash or replace the piston rings.

You can find more symptoms below, and links to the repair guides that explain how to fix the problem.


Troubleshooting Videos:

These repairs may help solve your Riding Mower and Tractor problem:

Replace the riding mower ignition switch

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.

For manuals, repair guides, and specific part recommendations, enter your model number.

Replace the riding mower ignition coil

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.

For manuals, repair guides, and specific part recommendations, enter your model number.

Replace the riding mower fuel pump

Fuel pump

The fuel pump moves fuel to the engine from the fuel tank on the riding mower or lawn tractor fuel tank. If the engine won't start or quits after starting, the fuel pump might not be working.

For manuals, repair guides, and specific part recommendations, enter your model number.

Replace the riding mower carburetor assembly

Carburetor

If the engine on your riding mower or lawn tractor is running roughly or only runs when the choke is partly on, you might need to replace the carburetor. 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 have peak performance.

For manuals, repair guides, and specific part recommendations, enter your model number.

Rebuild the riding mower engine carburetor

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. Seals and gaskets in the carburetor eventually wear out. Use a carburetor rebuild kit to refurbish a clogged or leaking carburetor.

For manuals, repair guides, and specific part recommendations, enter your model number.

Tune up the riding mower engine

Fuel filter

The engine tune-up includes routine maintenance for a riding lawn mower or tractor. This tune-up includes replacing the engine oil, oil filter, air filter, fuel filter and spark plug. The tune-up also includes checking the ignition, carburetor, battery, throttle and choke controls, as well as cleaning the engine cooling fins.

For manuals, repair guides, and specific part recommendations, enter your model number.

Replace the riding mower engine fuel filter

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. 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.

For manuals, repair guides, and specific part recommendations, enter your model number.

Replace the riding mower spark plug

Spark plug

The spark plug gets electrical current from the ignition system and sparks to ignite the fuel mixture in the cylinder, which drives the piston. The spark plug won't spark if it's coated with carbon deposits or oil residue, or if there’s a crack in the ceramic insulator. The engine won't start if the spark plug is bad. Replace the spark plug if it's damaged or coated with residue.

For manuals, repair guides, and specific part recommendations, enter your model number.

Replace the riding mower battery

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.

For manuals, repair guides, and specific part recommendations, enter your model number.