I have a 1983 GMC Seirra pickup that is blowing the ignition module. I have replaced 5 in the past 6 months. It appears to be blowing the module when the truck is off. I replaced the last one a week ago and started the truck twice immediately after the install. A week later and the truck will not start again. Can you tell me what might be happening with the ignition system? When I installed the module, I made sure the grease was spread evenly accross the back of the module to prevent overheating.
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Re: 1983 GMC Seirra blowing ignition modules
Another person (mountainman1) had this same problem with the HEI he found it to be a bad ground connection at the coil in the cap. When he would replace the module after replacing the cap it would make a new connection for a couple of days then go out again. I do not know if this is your problem but it sounds the same.
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don't worry about it, MOVE ON, replace the EGR VALVE, have you replaced both the air & fuel filters ? do it. make sure plug wires donot touch each other !!! do you have an ignition module in your distributor, if so replace it, be sure to apply silicone grease underneath where the module mounts, on distributor base, not the module. helps prevent overheating of module . replace your OXYGEN sensor, do it ! see how all this works, good luck !
Sounds like a short to ground in the ignition system, maybe the coil ? The computer grounds the module by way of the pickup coil in the dist. If the ignition module in the dist is actually being fried, it could be getting high voltage from the coil.
Try using heat sink grease between the metal base of the ignition module and the mounting position, from the sounds of it the circuitry is overheating and failing. I noticed that this particular module is very hot while the truck is running with my own Sierra
THERE IS A PICKUP COIL IN THE DISTRIBUTOR, IF YOU HAVEN'T CHECKED THAT, IT IS PROBABLY EASIER TO CHANGE THE DISTRIBUTOR THAN TRYING TO CHANGE JUST THE PICKUP COIL. MAKE SURE THE PICKUP COIL COMES IN THE NEW DISTRIBUTOR BEFORE YOU BUY. THE PICKUP COIL OFTEN CAUSES THE PROBLEM YOU ARE HAVING WITH YOUR CAR
What I see the most often is a stalled engine with a loss of spark when driving. Once the engine cools off it will sometimes start and run fine for a short while then do the same thing again. Often, but not always, the pickup up coil or ignition module [both are under the distributor cap] have to heat up quite a bit before they will act up. I replace about 10 ignition modules for every one pickup coil but either one can cause the same identical stalling problem. I keep a few known good modules around as test units so I can just replace a suspected bad module and road test it to see if it works. Another thing that can go wrong in these distributors are the magnets built into the pole piece. A weak or cracked magnet can cause all kinds of odd problems such as stalling when placed in reverse, misfires over 1,000 rpm, etc. Worn bushings in the distributor can also cause problems. As far as a specific test you can do to see which part is failing? I wish there was a relaible one. I've tried using a lab scope and module testers to diganose the culprit but you have to catch the problem as it's happening for those tests to be accurate.
Try disconnecting the four wire connector at the distributor,jumper terminals "A" and "C"(black to green) on the distributor side. this eliminates the ESC module and lets you deal with basic HEI. ohm the pickup coil 500-1500 ohms.use an ac volt meter white wire and green wire in the dist.,crank the engine.at least .5 vac,usually about 1volt.low voltage with a good pickup means a weak magnet.New cap& rotor? I've seen rotors burn thru...they look fine but will arc down to the advance weights.Make sure you have at least 9v at the big pink wire while cranking.disconnect any aftermarket tach,unplug the factory tach at the cap...If you installed a hi output coil,they are tough on ignition modules...Some things to try.