Troubleshooting a Lawn Mower Engine Problem

Updated February 21, 2017

Lawnmowers come in both push versions and riding versions and are useful gardening tools for manicuring your lawn. Because they get quite bit of use during the warm months, it is not uncommon for the engines to experience problems. If your lawnmower develops an engine problems, you can perform a series of troubleshooting steps to try and identify the cause. Most lawnmower engine issues are fairly simple fixes that homeowners can accomplish themselves.

Open the fuel shutoff valve if the engine will not start at all. Refer to your owner's manual for the location of this valve. If the valve is open or your model does not have one, proceed with troubleshooting.

Replace the spark plug if the engine will not start at all. Locate the cylinder-shaped plug on top of the lawnmower and remove it using a wrench. Take the spark plug to a hardware store and purchase an identical replacement. Screw the new spark plug into the engine and try to start it.

Start the lawnmower engine and wait to see if it starts to stutter or turns off. If so, turn the gas cap counterclockwise just until it starts to move. If the engine runs fine after loosening the cap, you have a clogged gas cap that is restricting air flow. Replace the gas cap.

Tilt the lawnmower on its side so that the carburettor is touching the ground. Locate the square air filter made of either paper or foam. Remove the filter to see if is clogged with dust. If so, it is restricting air flow to the engine, which causes it to sputter or turn off. Replace the air filter and try to start the engine again.

Remove all of the old gas and oil, and refill the tanks if the engine lacks overall power. Old gas and oil can clog the engine making it slower. You can tilt the lawnmower to drain out these liquids into approved containers or use a siphon.


If these steps do not fix the lawnmower problems, take it to a repair professional.

Things You'll Need

  • Spark plug
  • Air filter
  • Flammable liquid containers
  • Siphon (optional)
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About the Author

Kimberly Johnson is a freelance writer whose articles have appeared in various online publications including eHow, Suite101 and Examiner. She has a degree in journalism from the University of Georgia and began writing professionally in 2001.