How to Troubleshoot a Lawnmower Engine


Every year around spring time, home owners pull their lawnmowers out of little sheds (or from plastic coverings) and curse under their breath. Whether or not the mower engine will start is always a bit of a gamble if you do not prepare the mower for the winter months. It doesn't matter if it was laziness or something else, we've all done it. Getting your engine working when it is unresponsive does not need to be the same gamble. Following a proven set of troubleshooting techniques will get that engine pumping.

Will Not Start

Step 1

Check the engine to make sure it has enough gas and oil to run properly. Look inside the gas tank (with safety goggles on) to check the level. Use your dipstick, usually attached to the crankcase lid, to check the oil level.

Step 2

Replace the fuel if it is not fresh. Gasoline should not be kept in a mower tank over one month.

Step 3

Make sure you have the right mixture of gasoline and oil if your mower runs on a 2-cycle engine. Mix the fuel and oil according to the instructions on the oil packaging.

Step 4

Check that the spark plug is working by removing any gasoline from the area and touching the spark plug to a bare metal surface on the engine and try to start the mower. You should see a spark jump from the spark plug gap. If not, replace the spark plug.

Step 5

Check that the fuel cut-off valve is open (if your engine has one), so that the carburetor is getting enough fuel.

Intermittent Engine Use

Step 1

Check that the air filter is free from debris and dust. If it is a paper filter that is dirty, replace it immediately.

Step 2

Look for plugs in the fuel line with safety goggles and gloves on. Remove fuel lines and check for plugs.

Step 3

Unhook the carburetor from the engine and remove the top nut to look inside the carb for debris. Use carburetor cleaner if necessary.

Things You'll Need

  • Safety goggles
  • Work gloves
  • Socket wrench
  • Screwdriver
  • Old rag


  • Youtube: Troubleshooting your Lawn Tractor
  • M & D Mower: Small Engine Repair
  • Repairfaq: Notes on the Troubleshooting and Repair of Small Gasoline Engines
Keywords: troubleshooting lawn mower, mower engine troubleshooting, lawn mower problems

About this Author

Cleveland Van Cecil is a freelancer writer specializing in technology. He has been a freelance writer for three years and has published extensively on, writing articles on subjects as diverse as boat motors and hydroponic gardening. Van Cecil has a Bachelor of Arts in liberal arts from Baldwin-Wallace College.