Official Noma gas lawn mower parts

How to fix your Noma gas walk-behind lawn mower when its engine runs rough

If your lawn mower cuts out, smokes, idles poorly, vibrates or runs erratically, it could need a good tune-up to replace the spark plug, oil and air filter. Or the problem could be with the lawn mower's fuel system. Rebuild or replace the carburetor if the engine isn't getting a good supply of fuel.

If the engine misfires, backfires, sputters or jerks the starter rope out of your hand when you try to start it, the flywheel key could be broken. A broken flywheel key disrupts the ignition timing because the magnets aren't passing the ignition coil in synchronization with piston movement. Replace the flywheel key if it's damaged or broken.

Replacing the spark plug in your Noma gas walk-behind lawn mower

• When the engine is cool, disconnect the spark plug wire from the spark plug.
• Use a spark plug wrench to loosen and remove the spark plug.
• Use a spark plug gap tool to set the gap between the center electrode and the ground electrode. The gap specifications for your model are in the owner's manual.
• Thread the spark plug into the engine. Then tighten the spark plug with a spark plug wrench.
• Reconnect the spark plug wire and start the mower to make sure it runs.