This lawn mower repair guide shows how to install a new spark plug on a lawn mower. The spark plug ignites the air and fuel mixture in the engine to start the lawn mower. If the engine runs rough or is hard to start, check the spark plug and replace it with the manufacturer-approved replacement part if the enamel body is cracked or the electrode is fouled with carbon or other buildup. Manufacturers recommend changing the spark plug when you tune up your lawn mower each year.
Use this procedure to replace the spark plug in Craftsman, Husqvarna, MTD, Murray, Poulan, Toro, Troybilt, Snapper and Weed Eater walk-behind lawn mowers.
This video explains how to replace a spark plug on a walk-behind lawn mower.
Disconnect spark plug wire
When the engine is cool, disconnect the spark plug wire from the spark plug.
Disconnect the spark plug.
Remove the spark plug
Use a spark plug wrench to loosen and remove the spark plug.
Remove the spark plug.
Gap the new 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 owners manual.
Gap the new spark plug.
Install the new plug
Thread the spark plug into the engine. Then tighten the spark plug with a spark plug wrench.
Install the new spark plug.
Reconnect spark plug wire
Reconnect the spark plug wire and start the mower to make sure it runs.
These step-by-step repair guides will help you safely fix what’s broken on your walk-behind lawn mower.
Replace the ignition coil if it isn't sending electric current to the spark plug when you pull the recoil starter rope.
The flywheel key couples the flywheel to the engine crankshaft. Replace the flywheel key if it's broken.
The drive cable engages the transmission to spin the drive wheels and move the mower across the grass. Replace the drive cable if it's broken or frozen up inside the sheath.
Use the advice and tips in these articles and videos to get the most out of your walk-behind lawn mower.
See how to tune up your mower once a year to keep it running well.
Do these 5 things this spring for a lawn that's healthier all summer.
Prevent your mower deck from rusting by following our advice for keeping grass clippings from sticking.