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Interiors, Dash, Lights and Electrical Everything Inside

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  #1  
Old March 6th, 2022, 01:02 AM
newyorksong newyorksong is offline
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Default Not getting power to coil

Hi guys! Well my 1965 GMC 1000 just would not start after some very heavy rain. At first I thought the system was getting soaked and shorting out, or the coil was bad, but after buying a new coil now (no change) I think the yellow and black wires going to the coil positive might not be working.

The yellow and black wires go through the wall into what I don't know.
Any ideas?

Guess I'll see if the black is carrying 12 volts. Electrical is my weakest subject though it's a contest.

Thanks for any help
Roger
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  #2  
Old March 6th, 2022, 04:39 AM
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Default Re: Not getting power to coil

Whoa there Roger. Let's don't buy any more parts. You have reached the right place. We can get your truck started. First let's get the terms straight. "Won't start" I assume means it cranks just fine but will not even fire once? Starter is turning at good speed? I don't know why you think it is electrical. It could be. But it also could be fuel delivery or timing. Testing is the key right now. If you have a ice pick voltage tester or a multimeter, turn ignition key on and see if there is 12V at coil positive terminal (yellow wire). Don't try starting, just key to "on". Report. One step at a time. Answer all questions carefully.

Have you or anyone been messing with the motor or electrics? Is carb popping, backfiring, sputtering?

Last edited by AZKen; March 6th, 2022 at 05:10 AM.
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Old March 6th, 2022, 05:58 AM
newyorksong newyorksong is offline
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Default Re: Not getting power to coil

Hi Ken Thanks for responding. I went out and used my multimeter and the yellow wire (which also has a black wire on the positive terminal) showed 12v key on.
The negative of coil also had 12v.

No one has messed with it I just had it parked for a few months but always started it frequently until the rain and cold hit then one day it had trouble starting I gave it a lot of gas and the muffler blew apart like a grenade!

Since then it has started with worsening condition until it just quit for good.
No spark out of the coil.
Rog
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Old March 6th, 2022, 06:32 PM
gmcjuniorvan gmcjuniorvan is offline
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Default Re: Not getting power to coil

Electrical is not my thing so just a thought.
If you have 12v on the negative side of coil the points are open. That means when you check it they happen to be open or they are burn so bad they do not close all the way, you have a gap between them. . Have you checked the points?
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Old March 6th, 2022, 07:47 PM
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Default Re: Not getting power to coil

The next step is to remove a sparkplug. Attach it's wire to it. Touch the threads on a good clean metal ground spot on the motor and crank motor to observe spark. Hard to see in daylight, so watch carefully.
The backfire was probably your pumping gas, unburnt gas, into the system. It can also be something worse. Do the plug test and be sure of your result, very important.
I assume the negative on coil has a black wire to the distributor??????????? and that wire is not frayed and touching distributor housing.
I agree, probably time for new points and condenser of there is weak or no spark at plugs.
Explain specifically how you tested to get "no spark out of the coil".

Last edited by AZKen; March 6th, 2022 at 08:23 PM.
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Old March 6th, 2022, 11:07 PM
newyorksong newyorksong is offline
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Default Re: Not getting power to coil

How do I know there is no spark from the coil? Well your not gonna like this, no good mechanic does ... but I've been doing it for over 50 yrs and for me it is VERY accurate. What I do is HOLD the wire (from the coil or from a plug) as I put it to a spot on the engine, and believe me when I say I KNOW when I have a good spark or a weak spark or none! I could probably almost read you out the amperage by the tingle in my teeth. Embarrasing yes but there it is.
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Old March 6th, 2022, 11:20 PM
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Default Re: Not getting power to coil

BTW there are no points as the guy that had it before me put in the (what is the correct name?) electrical points thing. I could get a new condenser or a replacement electric points AND condenser if you think I should do that.

BTW pretty sure the carb may need to be rebuilt and I'm kinda short on $ right now so might have to do that myself but I am NOT very good a that kinda detail stuff.
Probably will have to do it. But right now I just need the truck to start to keep it oiled.
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Old March 6th, 2022, 11:25 PM
newyorksong newyorksong is offline
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Default Re: Not getting power to coil

Okay looked it up it's an electrical ignition. Sheesh Hmmm wonder it that could be bad?
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Old March 6th, 2022, 11:56 PM
newyorksong newyorksong is offline
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Default Re: Not getting power to coil

Don't know why pic is not showing but will put link here. Don't worry link is judt to my paid server and is okay!
http://syphan.phpwebhosting.com/carp...istributor.jpg
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Last edited by newyorksong; March 7th, 2022 at 12:01 AM. Reason: pic is not showing up
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Old March 7th, 2022, 12:01 AM
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Default Re: Not getting power to coil

Pertronix. There are good and bad reviews. The earlier versions had a lot of trouble. If I am helping someone with just words, which is VERY difficult, I have to do it a certain way, like you do. Unfortunately, I can't trust everything a person says and I have to have tests before I start jumping ahead or guessing. It's real easy to shoot out a dozen guesses. So let me know if there is spark at a spark plug. Maybe this one time you can look for a visual spark ay a plug like I described. I've been doing it that way for more than 60 years. We will establish spark and get truck started. Does not matter if fuel delivery is bad. Getting spark is No. 1 priority.
If you find no spark at a plug you can either revert back to points or we can try to troubleshoot the Pertronix/buy another.

Last edited by AZKen; March 7th, 2022 at 12:14 AM.
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