My Mower Engine Doesn't Shut Off Immediately

Damaged Wires

• Examine your mower’s diagram and locate all wires in the ignition circuit, including connections from the key switch or electrical starter button on a riding mower to the magneto. The ignition process consists of generating electricity that flows through a spark plug, which discharges and combusts to produce power. Look for any general damage like electrical arcing, tears or exposed wiring, all of which can cause a short in the system and prevent your engine from properly stopping.

Ignition Switch

• The ignition switch on your lawnmower may be shorted if you turn the key to the “off” position and the engine doesn't stop immediately. When you depress the starter button or turn the key, the switch connects two poles that signal the magneto to start generating electricity to start. Test the switch for resistance and replace as necessary.

Magneto

• Your lawnmower’s magneto generates electricity by repeatedly moving magnets on a flywheel past an armature. The movement creates a current that travels through a metal coil. When the circuit breaker trips, another coil receives the current and magnifies enough electricity to generate a spark through the spark plug. If your mower doesn't stop, the circuit breaker is likely faulty and didn't trip. Broken coil wires can also interfere with the starting and stopping process.

Negative Ground

• Whenever high-voltage electricity travels through parts, a negative or ground is needed to keep it from discharging elsewhere. The negative wire is often characterized as black or with a minus symbol. A grounding wire will sometimes have a small metal connection at the end designed to attach to an unlike metal. Check that ignition system wires are properly grounded and attached securely.