Find Local Contractor Call: 844-251-6308
No Obligation, Free Quotes
Home > Small Engines > What to Do When a Small Engine Won't Stop

What to Do When a Small Engine Won't Stop

By Karin Mangan
What to Do When a Small Engine Won't Stop

Whether you're using a chainsaw to cut tree branches or just mowing the lawn, it's a shock when you're finished with a job, yet your tool's small engine won't stop.

Once you release the tool's trigger or "dead-man" safety bar on the handle, the motor ought to die. This is how you kill the ignition to the small engine and apply a brake to the function of the tool, such as a lawn mower blade.

A more sophisticated machine might have a separate engine stop switch combined with a speed or throttle control to stop the engine. Until that is turned off, the motor will continue to run even though the tool's function will stop. Small engines with an electric starter sometimes have an ignition switch with the positions: stop, run, and start.

Most small gasoline engines don't require a battery. They generate power for the spark plug using a magneto, which is an electrical generator that creates a high-voltage pulse rather than a continuous current. A machine's ignition switch typically has one wire running to it. Turning the switch to off provides a ground to the magneto and shuts off the engine. But if you don't ground the magneto with the switch, the small engine won't stop. A faulty ignition switch will also cause the problem. Clean the wires and switch before you buy a new part. Excess dirt might be the culprit.

There are a couple of ways to turn off the engine until you are able to make the repair.

- Flip on the choke to let the engine stall.
- Use a wooden stick to pop the spark plug connector off the terminal to stop the engine.

Find a Pre-Screened Handyman
Enter Your Zip Code:


THIS ARTICLE IS PROVIDED 'AS IS' WITH NO WARRANTY OF ANY KIND. THE AUTHOR, THE SITE OWNER AND ITS AFFILIATES ASSUME NO LIABILITY FOR ERRORS OR OMISSIONS CONTAINED THEREIN OR FOR ANY USE OF THE INFORMATION CONTAINED IN THIS DOCUMENT. The article is for informational purposes only and is not a substitute for professional advice.