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#1
10-29-2016, 03:41 PM
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Cant shut engine off
I had this happen once, about 30 years ago and can't remember what solved it. It's a 69 Firebird, and it starts as designed. When I turn off the key it keeps running. I thought it could be the ignition switch, but I don't want to just start throwing parts at the car. Any ideas?
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#2
10-29-2016, 05:07 PM
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I would think it's the ignition switch. They are inexpensive and easy to change.
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#3
10-29-2016, 06:03 PM
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They are easy to replace. IIRC I put a new one in the car in 1986. I guess for $25 + shipping that's not a bad place to start. Thanks.
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#4
10-29-2016, 06:36 PM
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What do you have to do to kill it?
And when it's off is there power on the wire going to the coil? Did this happen on it's own or have you been doing other work on the car? Anything aftermarket or changed, like alternator, distributor, electric fans? This is kinda like playing 'twenty questions'. After a while you narrow it down to what the problem is. Clay
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All the federales say,they could've had him any day They only let him slip away, out of kindness...I suppose Poncho & Lefty |
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#5
10-29-2016, 10:02 PM
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As mentioned, any recent changes?
George
__________________
"...out to my ol'55, I pulled away slowly, feeling so holy, god knows i was feeling alive"....written by Tom Wait from the Eagles' Live From The Forum |
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#6
10-30-2016, 11:56 PM
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It happened on its own. I let the clutch out in gear with the key off to shut it down. It has no power to the ignition once its off. I did put an alternator on it after this condition started.
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#7
10-31-2016, 02:49 AM
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Aftermarket ignition box?
I know that MSD had/has a known issue with the idiot light circuit energizing the box when the ignition is 'off' for several decades.
To test with the MSD issue, start the engine and turn it off. If it still runs, unplug the two-wire connector on the alternator. If it dies, you found the problem. The MSD-verified fix is to install a diode in the idiot light wire. If you still have stock ignition, it's possible that your 'new' alternator has an issue and is feeding voltage back somehow. You could use the same test to rule it out. Turn the ignition off and then unplug the connector. If the engine dies, it's potentially something in the alternator. Good luck! |
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#8
10-31-2016, 01:30 PM
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Quote:
Quote:
Fixing to have more questions Clay
__________________
All the federales say,they could've had him any day They only let him slip away, out of kindness...I suppose Poncho & Lefty |
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#9
10-31-2016, 07:38 PM
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Ok. It doesn't have the reverse lock at this time. I replace the alternator because I thought it might be the issue.
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#10
10-31-2016, 07:59 PM
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Are we talking about "Dieseling or run on"?
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72 Luxury Lemans nicely optioned 
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#11
11-01-2016, 07:39 AM
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do as Joe's Garage said
Take (unplug) the alternator wires off and see if it shuts down. Possibly the alternator is still feeding back into the main harness. (bypassing the switch basically) Maybe the regulator also? (it's external right?) 
__________________
John Wallace - johnta1 Pontiac Power RULES !!! www.wallaceracing.com Winner of Top Class at Pontiac Nationals, 2004 Cordova Winner of Quick 16 At Ames 2004 Pontiac Tripower Nats KRE's MR-1 - 1st 5 second Pontiac block ever! "Every man has a right to his own opinion, but no man has a right to be wrong in his facts." "People demand freedom of speech to make up for the freedom of thought which they avoid." – Socrates |
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#12
11-01-2016, 11:56 AM
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If you have HEI or any distributor fed from a relay, or MSD box, this condition may happen..sometimes intermittently it seems.
In any case, adding a diode in series in the alternator indicator light circuit, banded end towards the alt, will take care of the issue, if the relay is the cause. George
__________________
"...out to my ol'55, I pulled away slowly, feeling so holy, god knows i was feeling alive"....written by Tom Wait from the Eagles' Live From The Forum |
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#13
11-01-2016, 04:01 PM
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Two More Things To Try
Cutting the engine off WITHOUT your foot on the brake pedal
And Cutting the engine off WITHOUT the steering columns lower collar in lock/reverse position. Faulty light sockets, bulbs, poor ground connections, in the rear of the car will let unswitched power feed back into IGN-1 and let the engine keep running. Seen feed back through the back up light circuit cause this a number of times. Just from a loose ground wire in the trunk. And as long as IGN-1 had power, from feed back, the alternator would continue to charge. Kind of a never ending cycle untill feed back power was cut and/or alternator quit charging. Then the coil + wire would be dead like it's suppose to be. HTH Just more stuff to look at Clay
__________________
All the federales say,they could've had him any day They only let him slip away, out of kindness...I suppose Poncho & Lefty |
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#14
11-01-2016, 08:29 PM
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Good info. Looks like I'll be checking all of these one at a time so we know what the final culprit was. Alternator is internal regulator unit. No dieseling, this this is ready to haul, as if the key was never turned off. This is a completely stock system. Hopefully I can get some time this weekend to go through all the suggested tests. This is the car in my Avatar.
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#15
11-02-2016, 11:11 AM
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Update. Pulled the taillight harness loose, didn't affect it. With ignition off I'm getting power at the coil. When I unplugged the alternator it did shut off.
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#16
11-02-2016, 01:44 PM
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Probably because of the one wire alternator.
Is the 'one wire' switched? Or just ran to battery? How are the original wires ran now? Putting a diode in should work I'd say. 
__________________
John Wallace - johnta1 Pontiac Power RULES !!! www.wallaceracing.com Winner of Top Class at Pontiac Nationals, 2004 Cordova Winner of Quick 16 At Ames 2004 Pontiac Tripower Nats KRE's MR-1 - 1st 5 second Pontiac block ever! "Every man has a right to his own opinion, but no man has a right to be wrong in his facts." "People demand freedom of speech to make up for the freedom of thought which they avoid." – Socrates |
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#17
11-02-2016, 02:28 PM
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A diode inline would work, but it does concern me as to why the stock system worked for 40+ years and then stopped. If the ignition switch is malfunctioning could it cause the alt to stay energized?
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#18
11-02-2016, 03:14 PM
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Once energized, the alt will continue to operate as long as the engine is running. A normal system with mech regulator, the ign sw breaks the connection to the coil from the battery and the idiot lite. The alt current backfeeding thru the light is not enuf to feed the ignition coil so the ignition dies, the alt stops, etc. Same thing with internal reg unit.
Are you certian there is no relay feeding the dist/coil? George
__________________
"...out to my ol'55, I pulled away slowly, feeling so holy, god knows i was feeling alive"....written by Tom Wait from the Eagles' Live From The Forum |
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#19
11-02-2016, 10:05 PM
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The electric system is completely stock, down to the AM radio. I don't think they ever used a relay for that purpose, did they?
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#20
11-02-2016, 11:48 PM
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QuickSilver, I've tried shutting it off but it doesn't work with my foot of the brakes. I have to shut it off in gear, and that's why I'm on the brakes, to keep the car from taking off.
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