Some of the most common lawn mower engine problems are a dirty, disconnected or loose spark plug, dirty air filter, flooded engine, leaky gasket and carbon deposits in the combustion chamber. These problems can cause a mower to knock, overheat or simply not start.
If a lawn mower does not start, the spark plug may be to blame. If the plug is dirty, the owner needs to clean it. If it is disconnected or loose, he must reconnect and tighten it, and if it has gone bad, he should replace it.
A dirty air filter can cause a mower not to start. The owner must clean or replace it.
An engine that does not start and smells of gas signifies a flooded engine. The owner can park the mower on a flat surface and allow the gas to evaporate. After 15 minutes, it should start.
A leaky gasket can overheat an engine. The owner must replace it.
A knocking engine often signifies the accumulation of carbon deposits on the combustion chamber. The owner need only clean the carbon from the head and piston.