1979 F150 ignition problems
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1979 F150 ignition problems
I have a 79 f150 with 400 and 4 speed. We pulled it out of the weeds and started wrenching. The truck will start and fire while cranking the starter. When you release the key to “run” it dies like you turned the key off. I’m not sure if it’s the ignition, wiring or engine electrical. Any ideas? Is there somewhere I should be seeing power with the key in “run” that might help me work back through the wiring?
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I’m getting the same voltage at the coil with key in “start” and “run”. That should let it stay running?
Cargo Master
Joined: Jul 2005
Posts: 2,309
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From: Kansas
not necessarily...the ignition module has to be getting 12v on the red wire as Yamhill mentioned...and the module has to be functioning correctly...I'm assuming the pickup module in the distrubutor is ok since it appears to be working during cranking.
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Tuned
Joined: Oct 2021
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From: Willamette Valley
one way to verify would be to put 12v on the red wire going into the module (not suggesting you go hacking up harnesses) and see if it fires off.
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Tuned
Joined: Oct 2021
Posts: 291
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From: Willamette Valley
oh, one more point: I'm talking about the red and white wires on the ICM side of the harness. at the interface connector, you may find that red and white nomenclature swaps. This seems to have been factory intentional, although I'm not really sure why.....
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to the OP.....this might be a long shot, but since you have a limited history with the truck....maybe someone installed an ignition 'kill' at some point?
one way to verify would be to put 12v on the red wire going into the module (not suggesting you go hacking up harnesses) and see if it fires off.
one way to verify would be to put 12v on the red wire going into the module (not suggesting you go hacking up harnesses) and see if it fires off.
Fleet Mechanic
Joined: Feb 2004
Posts: 1,508
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From: Arlington,Wa
Fact! I experienced this issue on my 79 a few years ago. I was poking around the ICM and noticed the red and white wires were crossed....so I spliced to them to match..red/red, white/white and it wouldn't start. It did what the OP describes. I swapped them back to the factory configuration and all was good so I left it alone.
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