Why Won't My Toro Lawnmower Start?

Gas

• Most often, problems with any lawnmower, including a Toro, occur when old or bad gas was either used or left in the tank. Gas only has a 30-day shelf life; after that, it will go bad. Using bad gas inside your Toro's engine will deposit sticky, gummy deposits in the fuel system. Dump out any old gas still left in the tank, following the procedure for the proper disposal of fuel. Rinse out the fuel tank with fresh gas, and scrub it with a rag and brush. Pull out the old fuel filter and replace it; do the same with the fuel lines if they're more than two seasons old. If the fuel problems continue, take the carburetor into a professional for a thorough cleaning.

Spark

• The spark plug provides the electrical energy built up in the engine with a way to discharge that energy into the cylinder. As the flywheel spins around the crankshaft, two magnets help build a charge within the ignition module's coil. Once a sufficient voltage is reached, the charge travels through the ignition wires and onto the spark plug. Replace your spark plugs yearly or more often if they get fouled easily. Check all the wiring connections and the condition of the wires. Replace any loose or damaged wires. Leave all other ignition repairs to a professional to avoid electrocution.

Air

• Your Toro lawnmower uses air in two separate ways. It cools the engine and helps vent gasses away, and it also brings air into the carburetor to mix with the fuel for better combustion. If these air ports get blocked, the engine will suffocate and won't start or run. Wash the foam element of the air filter every 10 hours of operation. Brush off the area around the carburetor and around the cylinder, including the cylinder's fins. Clean out the muffler, and wash the spark arrester screen every 50 hours of operation.

Compression

• Combustion delivers the necessary vacuum pressure needed to keep the fuel flowing, which in turn keeps the piston moving and the crankcase spinning. Without the proper pressure, the engine's systems will shut down and won't start. Compression issues occur when too much air gets into the internal engine, or when too much pressure builds inside the engine and can't escape. These problems occur usually as a result of faulty gaskets and seals. Compression problems will need a professional to diagnose and fix.