Engine run-on when ignition is off : Need Help !

[Stephan427SC]

Hi guys,
My engine continues running even when the ignition is turned off. Any idea how I can solve that problem...? I use a MSD 6 AL and a one-wire alternator. No external voltage regulator and no charging lamp as indicator. Will I have to install a small diode everywhere in that system...?

Thanks for your help,
Stephan

[DanEC]

Originally Posted by Stephan427SC

Hi guys,
My engine continues running even when the ignition is turned off. Any idea how I can solve that problem...? I use a MSD 6 AL and a one-wire alternator. No external voltage regulator and no charging lamp as indicator. Will I have to install a small diode everywhere in that system...?

Thanks for your help,
Stephan

Do you mean it diesels or has run-on . . . or do you mean it just doesn't stop when you turn the key off?

[donnieR32]

Mine continues to run sometimes after I turn the ignition off. Hell I've turned the fuel pump off and it will still go. Not until I hit the fan will it completely kill it.

[Stephan427SC]

It doesn't stop when I turn the key to off.....

[HM-BUILDER]

Im guessing it runs till it starves out of fuel. Sounds like you have your MSD power to a constant hot wire. Check that and if so find a keyed on only power source.

[Blas]

If possible, find the wire coming from the ignition switch to the starter solenoid. when the engine is running-on after the key is turner to off, disconnect this wire from the back side of the the ignition switch.... I'll bet the car turns off...

[Stephan427SC]

Blas,
startersolenoid and starter are wired like follows :
left side solenoid: Direct line to battery and to starter
right side solenoid : starter (small plug)
Front solenoid: starter-relais

[Blas]

Do you have a firewall mounted (or elsware) starter solenoid?
Also, is this a new problem or a new build debugging issue.

[Stephan427SC]

Blas,
it's a firewall mounted starter solenoid and a new build debugging issue.....
Thanks,
Stephan

[Blas]

Can you send me a photo of the Firewall mounted solenoid and the starter with the wiring. FYI: Normally, high torque starters have their own starter solenoid so the firewall mounted unit is redundant. You are in Germany? What brand replica?
My email is below

[Mike_I]

Do you have an electric cooling fan. If so, it could be the problem. Try running the fan off of a relay. Also make sure to break the signal on the relay when the ignition is turned off. Among other functions, the relay will also eliminate the fan back feeding voltage to the panel while it is still spinning down.

[Shelby Cobra]

I've been having the same problem with my CSX6000, several times when I turned the key nothing would happen, sometimes when I turned it off then went to start it back up nothing, had to let it cool down, then it started to not turn off (motor kept running) with the key off. I figured it was a bad ignition switch, Shelby American is sending me a new switch, so I will see if that was it. Funny about the fans, mine kept blowing the fuse, so maybe its not the switch, its something else.

[King- cobra]

I have had this same problem on two of my cars. The problem was cheaper seloniods. One was even brand new but the Autozone stuff is cheap. I went to Ford and bought one from them and have not had a problem. What happens is the seoniod sticks open so the key will not shut off the ignition. You may want to look at that.

[undy]

http://www.msdignition.com/instructi...pdf?terms=6421

Read pages 7 and 8... It fixed my problem which sounds that same as yours.

[Blas]

I note he has a one wire alternator which would render the dash mounted alternator light non-functioning (NOTE: All the external voltage regulator wiring should be removed or disconnected) so any bleed thru power from that dash mounted alternator light is eliminated from the electrical system. (This is in reference to the page 7 & 8 comment referred to earlier).
I know that radiator fans when turning from the air passing thru the radiator while driving can induce a small current into the system, but I would guess he is stopped when turning off the car….
Oh yes.... I have also heard of that dash mounted alternator light picking up a ground source from the dashboard - So try removing the bulb in the Red light housing and see if the problem disappears....

Stephan mentioned to me that he has already replaced the ignition switch. So it’s possible he connected the small red MSD wire to a hot post on the new ignition switch. I’m guessing the car runs till fuel pressure is depleted (assuming it has an electric fuel pump which turns off with the key)
Or the new ignition switch could be from a different manufacturer and wired differently than the original was or just faulty.

[Mike_I]

Originally Posted by Blas

I note he has a one wire alternator which would render the dash mounted alternator light non-functioning (NOTE: All the external voltage regulator wiring should be removed or disconnected) so any bleed thru power from that light is eliminated from the electrical system. (This is in reference to the page 7 & 8 comment referred to earlier).
I know that radiator fans when turning from the air passing thru the radiator while driving can induce a small current into the system, but I would guess he is stopped when turning off the

My electric fan was the culprit when I had the same problem as the OP. Electric fan still runs when your stopped. When the ignition was turned off, the fan still took a minute to stop spinning and continued to induce voltage to the system until it spun down. Adding a relay took care of the problem. The alternator can induce the same scenario as the fan on spin down that's why msd includes the diode in the kit. Finally, as others have mentioned there are several possibilities that the OP needs to eliminate to solve his problem. Turning off the fan completely before shutting down the engine would eliminate that possibility. Removing the field wire on the alternator would eliminate that one. Should be pretty easy to try these two real quick. Good luck.