Engine Stalls 

Some people look at yard and gardening work as a chance to get away from their daily stress and enjoy the pleasures nature has to offer, while others see it as a mindless chore that is to be gotten out of the way as quickly as possible. Regardless of the category you fall into, whenever it’s time to get to work, your power equipment, such as lawn mowers and garden tillers, must be able to do the job without adding to the task. The small internal combustion engines of most power equipment are simple and inherently reliable—but certain problems may crop up to make your day outside unpleasant. Few of those problems are more annoying than an engine that starts right up, boosting your spirits, and then stalls, preventing you from actually accomplishing anything.

Causes

Your power equipment engine, just like the gas engine in your car, truck or SUV needs three things to run properly—air, fuel, and a spark to ignite the air and fuel mixture. If any of these elements are not supplied to the combustion chamber in the proper mixture and at the proper time, your engine will not run smoothly and may not run at all.

The carburetor is used to mix the proper amount of air and fuel together and direct the mixture into the combustion chamber. Once in the chamber, your spark plug sparks at the proper time to ignite the mixture and apply a force to the piston, which drives your mower or tiller blade. 

Incorrect amounts of air or fuel will cause the engine to run sporadically or not at all, as will a weak or improperly timed spark.

What to Look For

Fuel - If this is the first time you have tried to run the engine since last fall, fresh gas may be in order. Gas will go stale in as few as 30 days, especially fuel mixed with ethanol as it is in many areas. Ethanol attracts moisture over time and the moisture will dilute the gas. 

Gas Cap – Most gas caps also function as a fuel tank vent, letting air into the tank as the fuel is used. The vent may be clogged to prevent air from entering the tank, resulting in poor fuel flow into the engine. 

Fuel Primer – Older engines have a small rubber bulb somewhere on the engine that should be pushed several times to prime the engine before starting. This injects a small amount of fuel into the carburetor to help the engine start. Newer engines have an automatic choke that accomplishes the same thing without any action from the user.

Air Filter – The engine air filter cleans the dust and debris from the air before it enters the carburetor. As it does its job, the filter becomes dirty and may become so clogged that the proper amount of air cannot pass through into the engine. 

What to Do

If you suspect a fuel issue, fill the tank with fresh gas and a small amount of gas starting/cleaning additive and give it another try. Remove the gas cap and clean the air vent. If the vent cannot be cleaned, replace the cap. Use the same technique on the air filter—if it cannot be adequately cleaned, it should be replaced. 

Other problems may also cause stalling, such as a bad ignition coil, worn or dirty spark plug, and a clogged fuel filter. Access to these items may require some engine disassembly and is best left to a trained mechanic specializing in small engines.

 If your engine needs new air and fuel filters, or a new spark plug, insist on a product from a name-brand manufacturer, such as Champion. Also, make sure that whatever parts you buy are genuine, not low budget knock-offs.       

Results

Once your equipment is up and running smoothly and consistently, be careful—the job may go so quick that you’ll get carried away and start mowing the neighbor’s lawn, or tilling your whole yard. 

The content contained in this article is for informational purposes only and should not be used in lieu of seeking professional advice from a certified technician. We encourage you to consult with a certified technician if you have specific questions or concerns relating to any of the topics covered herein.