68 gto starter run on - Pontiac GTO Forum
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post #1 of 16 (permalink) Old 06-18-2018, 08:36 PM Thread Starter
 
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68 gto starter run on

I'm about to fire a newly rebuilt Pontiac 400 with a 4 speed muncie.

Cranks over perfectly fine with no noise, whining or grinding, however intermittently the starter stays engaged and continues to crank the motor until I pull one of the battery cables.

So far, I've ensured the following:

1. the battery is fully charged
2. the engine and body grounds are both good
3. Starter was shimmed thinking that it might be binding
4. Starter bench tested fine
5. Key switch replaced

I'm at my wits end to say the least. My only thoughts going forward is that the solnoid for some reason is failing... not sure to be honest.

Any thoughts or suggestions would be appreciated.
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post #2 of 16 (permalink) Old 06-18-2018, 11:45 PM
 
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I had this happen to me over thirty years ago? I am getting old. It you have checked everything you said it is most likely a short. Next time it does it unplug your fuse at the fuse block and if it keeps running trace the wires. You go a short . You should bs able to track it down fairly easy . Best luck and let me know what you found Doug
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post #3 of 16 (permalink) Old 06-19-2018, 07:53 AM Thread Starter
 
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So you're saying to unplug the ignition fuse to see what happens? I'm not 100% sure how this would help me find the short
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post #4 of 16 (permalink) Old 06-19-2018, 11:28 AM
 
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hello

if it were me ... I would think solenoid ...

everything else sounds like its working fine ...

also ... just for proof ... just shave back a little insulation on the purple wire going to the starter
insert your test light or ohm meter ....

hit the key and start it ... if starter stays ingauged and light is off
starter issue staying locked in flexplate ... if light stays on,power is not shutting off the solenoid
and its staying engauged ....I would swap solenoids...

206 465 9165
Scott
home all day if you wanna chat ponchos ... multi 68 owner here also

clearance for the starter gear to the flywheel is a paper clip wire diameter .... just the old school tester

Last edited by BLK69JUDGE; 06-19-2018 at 02:58 PM.
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post #5 of 16 (permalink) Old 06-19-2018, 12:06 PM Thread Starter
 
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K so I just got back from the automotive electronics guy in my town. After I explained my issues to him, he had said that hes seen this in the past with delco starters. Says that in his 30 years of business hes seen this like 30 or so times and when hes contacted the delco engineers about the issue, he said that they advised him that once the engine starts, the gear would return.

I dont know.. has anyone else ever heard of this.

As for the multimeter... I did as you suggested and peeled some insulation off the purple wire. On run on, both the multimeter stays at 12 volts and the test light stays on.

I for some reason think that it might be a short. Does the purple wire run directly from the starter direct to the key switch, or is it going to be fuse block then to the key
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post #6 of 16 (permalink) Old 06-19-2018, 03:26 PM
 
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hmmmm

any body else ??

on our 68's we have the hot lead off the solenoid comes up top of the valve cover and is soldered into a "Y"

one to alternator the other to your ignition ... then the ignition sends power to the purple wire to activate

the starter solenoid .... release the key from sratrt to run and power to purple should end .....


Scott

being intermittant .... still feel its solenoid ...buy the good one from napa

be nice to the connector nuts ... no need to over tighten ....

heres a little reading
https://www.google.com/search?ei=8GU....0.vkWlibxOXc8
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post #7 of 16 (permalink) Old 06-19-2018, 03:34 PM
 
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I've seen several things that will do that. One was a broken drive return spring, solenoid magnetized and not releasing the contact plate, Ign switch shot, hot wire to the coil miss wired, purple start, yellow goes to the hot side of the coil via the ign switch I think on the 68 to give it 12vdc for start. If the purple and yellow wire are connected to the same post at the starter you will have problems. Good luck.

Last edited by Bob Young; 06-19-2018 at 03:51 PM.
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post #8 of 16 (permalink) Old 06-19-2018, 04:43 PM
 
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"however intermittently the starter stays engaged and continues to crank the motor until I pull one of the battery cables. "

this is the clue

intermittently

solenoid spring limp ? sticky throw piston ...

try not to overthink it .............. yah ok ................

AND

when its off the starter and purples hangin there ... do your test with key for power at the end of the purp ...

should eliminate your ignition if the light reacts to the key being turned
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post #9 of 16 (permalink) Old 06-19-2018, 08:08 PM Thread Starter
 
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Yes I have tested the purple wire when not hooked to the starter. Test light goes on and off as it should with the turning of the key.
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post #10 of 16 (permalink) Old 06-19-2018, 08:12 PM Thread Starter
 
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Bob young... the cars been changed to hei so I only have the purple from the ignition going to the "s" terminal and the battery cable along with another wire on the same large post as the positive battery cable going to the alternator.
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