Weed eaters, also referred to as weed trimmers or string trimmers, come equipped with a kill switch. This switch is typically located on the handle, near the operating trigger. This is a red toggle switch the operator depresses to shut the gas engine off. This switch may begin to malfunction after many hours of regular use and eventually fail. When a weed eater kill switch fails, it can be replaced by the owner at minimal cost.
Let the weed eater cool down before attempting to replace the kill switch.
Set the lawn tool on an elevated surface, such as a table or workbench, to avoid having to bend or crouch over to work on the machine.
Unfasten the retaining screws at the base of the kill switch over the handle/shaft with a screwdriver or hex wrench, whichever is applicable to your specific make and model of trimmer.
Pull the old kill switch off of the weed eater's handle. You will see wires running from the underside of the kill switch down through the shaft or handle to the engine.
Locate the wires that supply power to the kill switch on the engine. You may have to remove the spark plug with a ratchet and socket to access the kill switch wires.
Unplug the kill switch wires by hand or use a pair of pliers. Pull the kill switch wires out through the shaft and discard it.
Feed the wires of the new kill switch into the shaft and out to the engine. Plug the new kill switch wires in where the old kill switch wires were plugged in then fit the new kill switch into place on the shaft and fasten it with the screwdriver or hex wrench.
Replace the spark plug to finish, if applicable. Start the weed eater and depress the new kill switch to test it.