What to do if your lawn mower won’t start?

When you dust off your mower, push it into the springtime sun, you can nearly smell the freshly-mowed lawn. But if you’re like us, every once and a while, you’ll find that the engine won’t start.
If your lawn mower won’t start, the first thing I’d do is use an ignition/spark tester.
As the owner and operator of a residential and commercial landscaping care business for 25+ years, an ignition/spark tester was my go-to tool if an engine failed to start. With an easy-to-read terminal screen, this tester helps you troubleshoot and determine the most likely cause of the equipment’s failure to start such as a dead spark plug, a bad ignition coil or something else. It will save you a lot of time.
RepairClinic has free troubleshooting and repair help information for this lawn mower problem and many others.
The most likely cause of a lawn mower engine not starting
There are many causes for engine failure but by far, the most common cause is a faulty spark plug.
Fortunately, replacing a spark plug is simple.
Always read your lawn mower’s owner manual’s instructions for spark plug replacement. Be sure to use the exact spark plug recommended for your engine. Using an alternative spark plug can cause serious engine problems.
Here’s how to replace a lawn mower engine spark plug:

1. Make sure the engine is cool.
2. Remove the wire and boot from the spark plug.
3. Use a spark plug wrench to remove the old spark plug.
4. Install the new spark plug with care by tightening it onto the cylinder head. Be careful not to over tighten or damage the plug.
5. Attach the spark plug wire and boot.