Lawn mowers should run smoothly. A puttering motor is a sign of a dirty engine, improper maintenance or a carburetor that needs adjusting. Before taking your mower to a repair technician, you can take several troubleshooting steps to try and solve the issue. Some repairs, however, are better left to a certified repair technician; when adjusted incorrectly, a carburetor will wear out quickly and potentially cause damage to the mower engine.
Things You'll Need
Unscrew the lid of the gas tank and inspect the gas level. Gas that is too low will cause the engine to idle poorly and putter. Replace gas if it is fouled with water or over a month old.
Remove the screw holding the air filter cover in place, or press down on the clips to remove the cover. Replace a dirty paper filter or wash out a foam filter using dish soap and water.
Remove the spark plug from the engine using a socket wrench. Inspect the ends for signs of fouling. Check the gap of the spark plug using a spark plug gapping tool, available from most hardware stores. Compare the gap measurement to the recommended spark plug gap in your mower owner's manual.
Take your mower to a professional to have the carburetor adjusted.
Check that the choke handle is set in the "fast" or running position. A low choke setting will cause the engine to putter.
Inspect the throttle cable leading from the choke handle to the engine. Ensure that it is attached to the choke on the engine. Tighten the screw holding the cable in place to tighten it.
Unscrew the clamps for the fuel line which leads between the gas tank and the fuel filter. Remove the line and inspect the line for clogs. Blow out the hose with compressed air and reinstall.
Remove the fuel line from both sides of the fuel filter. Unscrew the old filter and attach a new one to the fuel lines.