Trimmer: Can't Turn Engine Off

The switch turns the power off at the ignition module to stop the current flowing to the spark plug. When set to the on position the current will flow. If you cannot shut the engine down with the switch then you probably have a malfunctioning switch. Disassemble any covers you need to gain access to the switch. Check that all the switch wires are intact as well as at the ignition module. Remove the switch if all the wires are connected. Check the switch with an OHM meter for continuity. The readings should be different from the on/off position. If the reading stays the same for both positions then the switch is bad. Install a new switch, hook the wires back up, and re-install the covers.

The coil has two wires coming from it. One is the spark plug wire and the other is the kill switch wire. The kill switch wire gets grounded to kill the spark and shuts down the engine. If that wire is broken, the engine will keep running. To check this, remove the cover or covers exposing the kill switch and ignition module. Follow this wire from the ignition module to the switch. If it has broken off, reattach the wire or replace the whole wire. Re-install the cover.

This part produces the electrical charge for the spark plug, through magnets on the flywheel rotating past the magnets on the module. If the metal part going into the ignition module is loose, it can cause internal problems such as a bad ground inside of the module. This can cause the engine to keep running when you shut off the kill switch. Remove any covers you need to access the switch and ignition module. Remove the ignition module and check the metal connectors for tightness going into the coil. If you can wiggle them around you should replace the coil, even if it is working properly, as it will get worse with vibrations from the engine. Install a new coil and hand tighten the bolts. Insert a business card in between the flywheel and the module, next rotate the flywheel magnets to the ignition module, allowing the magnets to pull the ignition module into place. Tighten the module down and remove the business card. Re-install the cover.