Lawn Mower Doesn't Pull-Start

Starter Rope Problems

• The only visible part of the starter system is the starter rope, which gets pulled out every time you fire up the engine. This rope is wrapped along a pulley that helps it retract after it gets pulled out. If the starter rope can't adequately spin the pulley, the flywheel also won't get spinning fast enough for combustion to start. This rope can get covered in dirt, oil and other sticky substances. If the rope pulls out in bursts or looks frayed or torn, replace the rope.

Recoil Mechanism

• The recoil mechanism works in the starter system to allow the operator to continuously crank the engine again and again until the engine fires. The recoil mechanism consists of a pulley, which holds the rope, and a recoil spring cassette inside the pulley. When the rope gets withdrawn, the spring stretches out, and when you let go of the rope, the spring causes the rope to wind back onto the pulley. If the pulley is cracked or riding rough on the starter post, it won't spin fast enough. If the recoil spring is damaged, it won't allow the rope to retract.

Flywheel Damage

• The pulley and recoil mechanism sit atop the flywheel. When they spin they cause the flywheel to spin as well. The flywheel helps build up the magnetic energy needed to force the ignition module into releasing its spark up the plug wire and to the spark plug. Damage to the flywheel will cause it to spin erratically along the crankshaft and cause the entire starter system to be out of time. If the lawn mower hit a rock while running at full speed, the flywheel or flywheel key may have gotten bent.

Compression Loss

• Compression creates the necessary vacuum pressure needed for the moving parts to keep moving. Without compression the engine won't fire or stay running. A loss in compression usually occurs around worn out valves leaking air into the internal engine. Another common cause of compression loss occurs when the bore gets rough and can't move properly in the cylinder. Compression problems often require that you replace the engine, which may outweigh the cost of a replacement mower.