How to Fix a Lawnmower That Will Not Start

Lawnmowers use a small internal combustion engine that usually operates with a four-stroke engine process. These engines require three basic elements to start and run: fuel and air mixing inside the carburetor, compression from the crankcase to keep the systems cycling and a spark to combust the fuel/air combination. When one of these three elements is missing, the entire process will be out of alignment, and, most often, the lawnmower will not start.

Approved fuel container
Fresh lawnmower fuel
Rag
SAE 30 oil
Socket wrench
Replacement spark plug

Instructions

- 1
  Open up the gas tank and check the supply of fuel in the tank. Dump out any fuel that's older than 30 days into a fuel container. Refill the tank at least three-quarters full with fresh lawnmower fuel.
- 2
  Unscrew the oil dipstick, wipe off the end and reinstall it. Pull out the dipstick and check the reading. Add more SAE 30 oil --- for operating temperatures above 32 degrees Fahrenheit --- to the oil spout slowly until the reading on the dipstick says "Full."
- 3
  Move the ignition switch into the "On" position. Check the electrical connections on the wires to make sure they aren't loose or broken. Move the transmission, if applicable, to "Neutral." Unhinge the rubber boot from the tip of the spark plug. Unscrew the spark plug from the cylinder and reinstall a new plug.
- 4
  Unhook or unscrew the cover to the air filter box. Pull the foam element out of the box and clean the filter according to your manufacturer's specifications. Replace any old filters. Wipe the area around the box and carburetor with the rag.
- 5
  Check the routing of the fuel lines to make sure they aren't kinked or ripped loose. Pull out and replace the fuel filter every season. Replace the fuel hoses every other season or more frequently if necessary.

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