How to Troubleshoot Lawn Mower Problems

Overview

Lawnmowers have many potential problems which can cause them to function improperly. Fortunately many of the problems can be eliminated or solved with simple maintenance. When you troubleshoot lawnmower problems, there are always common issues to look for. Once you develop a list of these common problems, troubleshooting becomes much easier. You should always disconnect the spark plug wire before working on any part of the lawn mower to avoid accidental start-up of the engine.

Mower Will Not Start

Step 1

Unhook the spark plug wire. Use the spark plug wrench to remove the spark plug. Check the plug for dirt or damage. Check the wire for dirt or damage. Clean both the spark plug and the end of the wire with a wire brush. Screw the spark plug back into the mower, and reattach the wire.

Step 2

Unhook the battery. Remove the battery from the lawnmower. Attach the battery to the charger to check how much of a charge the battery has. Clean the battery cables with the wire brush while charging the battery. Put the battery back into position once you know it is fully charged. Reattach the cables.

Step 3

Check the fuel and oil. Make sure you have the proper amount of each in the correct chamber. Check the color of the fuel and oil. If it is dark or black you must change the fluid. Siphon out the fluid, and replace it with new fluid.

Step 4

Disconnect the spark plug wire. Unhook the fuel line. Remove the carburetor and filter. Clean out the fuel line with hot water. Clean the carburetor with hot soapy water. Replace the filter. Allow the fuel line and carburetor to dry. Reassemble the filter, carburetor and fuel line.

Mower Stops During Mowing

Step 1

Check the fuel and oil levels. Make sure these are filled to the proper amounts. Fill the fuel and oil reservoirs with the correct amount of fluid. Try restarting the mower.

Step 2

Look over the engine for air leaks, which could result from small holes forming in the casing, bolts being loose or missing or gaskets being worn, cut or missing.

Step 3

Tilt the mower up to check the blades. Lift the mower by the side which has the spark plug, keeping the spark plug pointed up so it doesn't get drowned in oil. Look at the blades under the mower, checking for obstructions, broken or bent blades. Check the crankshaft for looseness or binding. Check the fly wheel to make sure it hasn't snapped or been damaged. Replace any broken parts.

Step 4

Check the carburetor and air filter. Unhook the fuel line. Remove the carburetor and filter. Clean out the fuel line with hot water. Clean the carburetor with hot soapy water. Replace the filter. Allow the fuel line and carburetor to dry. Reassemble the filter, carburetor and fuel line.

Mower Runs Rough

Step 1

Check the fuel and oil. Look at the color of the fluid; if the color is dark or black, replace the fluid. Siphon out the fluid, and replace it with new fluid.

Step 2

Check the spark plug. Unhook the spark plug wire. Unscrew the spark plug. Check the spark plug for dirt or corrosion. Clean the tip of the spark plug with the wire brush. Clean the inside of the chamber where the spark plug fits. Reinstall or replace the spark plug. Reattach the spark plug wire.

Step 3

Check the carburetor. Disconnect the fuel line. Remove the carburetor, and clean it out. Look for any damage while cleaning. Replace the air filter with a fresh unclogged filter. Reassemble the carburetor and line.

Mower Stops and Doesn't Restart

Step 1

Check the fuel and oil levels. If either drops below a certain limit in the reservoir, the mower will stop. Fill the fuel and oil to proper levels.

Step 2

Check the spark plug to make sure it hasn't been fouled. Look for dirt or excess oil. Clean the spark plug, wires and chamber with the wire brush.

Step 3

Double check the throttle lever to make sure it is not in the "off" or "choke" position, which is the same as having a car in neutral as the mower engine will not engage

Mower Vibration

Step 1

Check the blades to see if they have become loose. Lift up the mower from the spark plug side to keep the spark plug from drowning in oil. If the blade wobbles or has play, tighten it.

Step 2

Check for debris or obstructions underneath the mower deck, which can cause the mower to wobble because normal vibrations are amplified from the mower carrying extra material.

Step 3

Check for loose bolts or screws around the engine or engine housing. These can not only cause vibrations but can impact the operation of the engine and can potentially cause injury if they are shot free of the lawn mower.

Things You'll Need

  • Spark plug wrench
  • Gas
  • Oil
  • Air filter
  • Screwdriver
  • Adjustable wrench

References

  • Home Services Engine: Tips on Mower Trouble
Keywords: lawn mower problems, troubleshooting mower problems, lawn mower maintenance

About this Author

Jack S. Waverly is a Pennsylvania-based freelance writer who has written hundreds of articles relating to business, finance, travel, history and health. His current focus is on pets, gardens, personal finance and business management. Waverly has been writing online content professionally since 2007 for various providers and websites.