1992 Sierra keeps blowing module

[millennium_knight]

I've owned a number of GMC/chevy trucks ranging from 88 to 94, never had this problem before, and I can't find the problem. I have a 1992 GMC sierra k1500 4x4. In January my problem began. One morning I went to start my truck and all it would do is turn over, but no fire. First thought was the module, although the engine is only a year old the distributor is original except for the pickup coil. So I replaced the module and the truck fired right up. roughly 2 weeks later same problem. I figured "Ok I had a defective module" (rare for echlin but it happens) replaced it again, truck fired right up. Again roughly 2 weeks later, no start. I'm on my 5th module (all warrantied so not out much cash) This last module was the high end one and it's now blown. I know it's got to be a short/ground problem, but I can't find it. Anyone got any clues or if something else is causing it and that it's not a ground/short issue.

[sherman69]

Originally Posted by millennium_knight

I've owned a number of GMC/chevy trucks ranging from 88 to 94, never had this problem before, and I can't find the problem. I have a 1992 GMC sierra k1500 4x4. In January my problem began. One morning I went to start my truck and all it would do is turn over, but no fire. First thought was the module, although the engine is only a year old the distributor is original except for the pickup coil. So I replaced the module and the truck fired right up. roughly 2 weeks later same problem. I figured "Ok I had a defective module" (rare for echlin but it happens) replaced it again, truck fired right up. Again roughly 2 weeks later, no start. I'm on my 5th module (all warrantied so not out much cash) This last module was the high end one and it's now blown. I know it's got to be a short/ground problem, but I can't find it. Anyone got any clues or if something else is causing it and that it's not a ground/short issue.

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Hi,
On my wife's car, there was a missing jumper at the coil. When I replaced the module, along with the cap and rotor, I read an instruction that pointed out the jumper that must be there.
The coil has four screws that mount it to the cap. under one you put the black wire from the coil. but there needs to be either a black wire or metal jumper under one of the screws that plugs into the center slot on the cap, it supplies the ground to the coil secondary. Apparently someone lost it nand the car ran ok for some time before the coil and module went bad.
Bob B

[1thunder]

not shure if this your problem but i learned that these modules in the distributor need a light layer of dielectric greese under the module this apparently cools the module transfers heat to distributor plate should try it apperently this is GMC knowledge and suggestion as a fix for this problem

[fuzzypuppy]

I can atest to the dialetric grease, I forgot to regrease mine after working on my dist and it blew a few weeks ago, although mine lasted almost a year with no grease, I just installed the accel unit, it came with the grease in a packett, I used it all, have had no prob since. also I have a 91 and there is no ground wire on myne at all. if you have not used the grease id say that there is your problem, if you do, check for shorts, i have had to go through and clean up all the wiring in that area of my truck, the top of my coil was shorting out on the bottom of my air cleaner, so i mounted mine on the firewall just above the dist in a horizontal position. replaced all the split loom, greased all my connections to prevent moisture and corrosion problems, while doing all this clean up i caught a few potential future problem spots, hope this helps good luck,

[millennium_knight]

I've used the grease everytime on it, so I know it's not that. I've been going through the wires trying to find the short but no luck so far.. one things is for sure, if you don't have patience forget trying to figure out an electrical problem.

[1thunder]

just a thought are you using resistor type plugs and your high tension wires ok and not arcing when
wet try spraying water on them to check

[millennium_knight]

I was using Bosch Platimun plugs, now I have in AC Delco Rapid Fire Platinums, and the wires are new Belden Premium. I checked for arcing and they are fine.

[millennium_knight]

Yet another twist to the problem.. I torn down the top end of the distributor, basically getting ready to pu tin a new module (#6) and decided to put the existing module (#5) back on. I cleaned the old grease off put new grease on the module, mounted it, put the distributor back together. Turned the Key and it fired right up. I'm sure it'll crap out on me again becuase I still haven't found the problem. now I have a new twist to it.

[2000CAYukon]

Maybe the problem is with your coil and not the ignition module. I had a MSD coil in my K1500 and the truck died one day. The coil was less than a year old so I figured it was the module. Turned out it was the MSD coil. Put the stock one back in and it has been fine ever since.

Might not hurt to check the coil.

//2000CAYukon

[millennium_knight]

The pickup coil was a new echlin, I also though of it possibly going bad and being the problem. The pro techs kept telling me if it was bad the truck would run like crap. regardless of that I tested the coil and it tests fine. It should test between 500 and 1500 ohms. mine was 768 and it didn't fluctuate when I flexed the harness, which is what you want. if it varies with the flexing of the harness it has to be replaced. I may pull the whole HEI distributor our and replace it as I'm running out of options.. One test I did, which will indicate a ciruit problem, is test the voltage at the TACH. if the circuit is good (with the key in the on position) the tach will read a minimum of 10v, mine reads 12V which is good. The ohm readings on the starter coil were also correct.

[2000CAYukon]

Originally Posted by millennium_knight

The pickup coil was a new echlin, I also though of it possibly going bad and being the problem. The pro techs kept telling me if it was bad the truck would run like crap. regardless of that I tested the coil and it tests fine. It should test between 500 and 1500 ohms. mine was 768 and it didn't fluctuate when I flexed the harness, which is what you want. if it varies with the flexing of the harness it has to be replaced. I may pull the whole HEI distributor our and replace it as I'm running out of options.. One test I did, which will indicate a ciruit problem, is test the voltage at the TACH. if the circuit is good (with the key in the on position) the tach will read a minimum of 10v, mine reads 12V which is good. The ohm readings on the starter coil were also correct.

I was refering to the ignition coil not the pickup coil. I have seen them work fine cold but act funny when the get warm/hot.

//2000CAYukon

[millennium_knight]

[quote=2000CAYukon]I was refering to the ignition coil not the pickup coil. I have seen them work fine cold but act funny when the get warm/hot.

This would be the reverse, it would act up when it was really cold, but run fine warm/hot.

[1thunder]

i had coils run good cold then crap out hot many times