Why Won’t My Mower Start? 7 Common Causes

"Cranks but won't start" and "won't even crank" are two different problems. Work through these in order — most no-start issues trace back to one of these seven causes.

1. Stale or wrong fuel

The single most common cause. Old gas loses volatility; ethanol-blended fuel left too long can also gum up the carburetor jets.

2. Fouled or worn spark plug

No spark, weak spark, or an incorrectly gapped plug will prevent ignition even with fuel present.

3. Clogged air filter

Restricts the air side of the fuel/air mixture — can cause hard starting or stalling immediately after starting.

4. Dirty or stuck carburetor

Especially after storage — varnish from old fuel gums up the float bowl and jets.

5. Safety interlock not satisfied

Riding mowers won't crank unless the seat switch, brake switch, and PTO switch are all in the correct position — check these before assuming a bigger problem.

6. Weak or dead battery

Slow or no crank on electric-start equipment is very often just the battery.

7. Flooded engine

Repeated starting attempts with the choke on can flood the cylinder. Let it sit a few minutes with the choke off and throttle wide open, then try again.

Describe your exact symptoms on the Service tab for a guided diagnostic — including the confidence-scored root cause and parts needed for the fix.