With what I believe is the “normal” way most people have their wiring setup:
Their cut-off switch wired breaking the “+” cable to the battery.
Their alternator/voltage regulator power out connection is wired to the hot side of the starter solenoid…or to be more generically said; power supply connected up-stream of their battery cut-off switch…
Scenario “A”: With an electric fuel pump…
Flipping the cut-off switch will not shut off the engine immediately.
The car will continue to run until the remaining fuel/fuel pressure is eliminated because the ignition system in powered “up stream” of the cut-off switch by the alternator.
Scenario “B”: With a mechanical fuel pump.
Flipping the cut-off switch will not shut off the engine…
The car will continue to run because the fuel pump is mechanical activated by the running engine, and the ignition system in powered “up stream” of the cut-off switch by the alternator.
The Fix:
You need to run the alternator charge wire to the battery side of the cut-off switch or directly to the positive terminal of the battery. When wired properly, the car should turn off when the switch is turned off. If the alternator is feeding between the switch and the engine, it will still run even if the switch is turned off.
Note: You must run the positive (+) cable to the cut-off switch, not the negative.
Thought this might be of interest to some of you. Came across it purely by chance when a local owner got curious and flipped his cut-off switch with the engine running…car kept running for a while…SURPRISE
