What might cause an engine to keep running when the magneto switch is turned to "OFF"?

The situation where an engine continues to run after the magneto switch has been turned to "OFF" is often related to issues with the grounding system of the magneto. In this case, if there is a broken magneto ground wire, the electrical system may not be completing the circuit that is designed to shut off the spark to the engine.

When the magneto switch is turned to the "OFF" position, it is supposed to connect the magneto output to ground, effectively stopping the engine by preventing spark generation. However, if the grounding wire is damaged or broken, the connection is lost, and the magneto can continue to produce sparks, allowing the engine to keep running even when the switch is in the "OFF" position. This indicates a failure in the electrical system designed to control the ignition.

Other options, such as a faulty spark plug, an empty fuel tank, or low oil pressure, do not directly affect the ignition system in this manner. A faulty spark plug may cause engine misfires or rough running, but it wouldn't cause the engine to continue running after the ignition is supposed to be off. Similarly, an empty fuel tank would result in fuel starvation and cause the engine to stop running, not continue. Low oil pressure might