Engine will not shut down when key is turned off.

[AROCK]

I have checked everything g possible to correct the problem to no avail. I need help !!I have disconnected fan and alternator from the ignition switch and engine still does not stop. All help would be appreciated.

[Morrisett]

Hey there, not sure what engine your running but I had a old cj-5 with a tbi 350 in it and when the engine would get up to operating temp the electric fan thermostat would activate backing feed to the fan override switch and then back feeding to the ignition causing the engine to continue to run with the ignition off. As soon as I would turn off the fan switch it would kill the engine. Probably not your exact case but maybe getting you thinking down a path of how you wired the ignition?

[AROCK]

I have a Ford 427 stroker
Just built it and installed in Mark 4. I wired as per Ron Francis drawing.
In attempt to chase down the problem I disconnected the Fan, I also disconnected alternator. Still would not shut off. I also put a diode in the alternator circuit, as well as a resistor on the small red lead on the MSD 6 AL.. I have changed the ignition switch twice. Still does the same thing when I remove the Battery lead from the switch when the engine is running it does shut engine down. But that is not solving the problem.

[edwardb]

What is the small red wire from the MSD box attached to? It has to be a switched connection. My guess is you have it on a battery connection (e.g. always on) so even though you turn the key off, the MSD box is still alive and keeping the engine running. Would be easy enough to test. Try disconnecting the small red wire while the engine is running. That should turn off the MSD box and the engine should stop. Not sure what you expect a resistor in that line to do. And unless it's a really large one, I wouldn't have a diode in the alternator line. There's no purpose and likely it's just going to get hot or even overload and open up.

[AROCK]

Thanks for your response. I have the small red wire on the MSD box wired to the battery side of the ignition switch. It should shutdown engine when turned off?
I also have kill switch wired in that supplies battery to everything. When I cut the kill switch off it kills the engine.
The ignition switch is wire according the the supplied drawings g for Ron Francis wiring harness.

[edwardb]

Thanks for your response. I have the small red wire on the MSD box wired to the battery side of the ignition switch. It should shutdown engine when turned off?

Yes. That small red wire is the "sense" wire for the module. Tells it when to turn on and off based on the ignition switch. That's the meaning of the ignition switch logo in the MSD wiring diagram and explained in the MSD instructions. Having that wire on a constant battery source will not only keep your engine from turning off, as you experienced, it will also leave the MSD box running all the time and eventually drain your battery.

[AROCK]

Thanks, that is the reason for the kill switch. It is turned off when I try and shut down car. The engine does shut off when I disconnect the MSD wire from ignition switch, but isn't the purpose off the switch to also shut off MSD when switch is turned off?
I have a 45 year drag racing back ground running Prostock and we always wired the 7AL box to it's own switch then a start button. Never experienced having to use an ignition switch which is confusing to me when I expect everything that was wire separately to work on an ignition switch and it doe not.

[edwardb]

Thanks, that is the reason for the kill switch. It is turned off when I try and shut down car. The engine does shut off when I disconnect the MSD wire from ignition switch, but isn't the purpose off the switch to also shut off MSD when switch is turned off?
I have a 45 year drag racing back ground running Prostock and we always wired the 7AL box to it's own switch then a start button. Never experienced having to use an ignition switch which is confusing to me when I expect everything that was wire separately to work on an ignition switch and it doe not.

I don't know what to tell you other than to wire it like the MSD instructions show and the engine will shut off with the ignition switch. That was your original question and with that red wire hot all the time the root cause. I don't have your years of experience. But I've done several MSD boxes and they always worked per the instructions. Good luck.

[Jhinkemeyer]

I don't know what to tell you other than to wire it like the MSD instructions show and the engine will shut off with the ignition switch. That was your original question and with that red wire hot all the time the root cause. I don't have your years of experience. But I've done several MSD boxes and they always worked per the instructions. Good luck.

This is the correct answer, the MSD instructions usually show this pretty well and explain it as edwardb stated. The kill switch circuit has use in some applications, but the switching on and off under normal conditions is done via the small red wire tied to the IGN post of the switch (not the BAT) as described by edwardb. Pretty sure the RF harness has a wire for this already fused and ready to go that I grabbed and used.

[AROCK]

Thank for the responses I received. I will move the small red wire to the ignition post on the switch and see what happens.
Thanks again you guys have been a great help.

[AROCK]

Thanks EdwardB and jmeyer you were ded on the wires were switched and the engine now shuts off!! Thanks guy's

[Jhinkemeyer]

Thanks EdwardB and jmeyer you were ded on the wires were switched and the engine now shuts off!! Thanks guy's

Congrats!

[AROCK]

Now I can put on tires and go-kart , yea!