Novice here. Bear with me on the details that you want that I've left out. I'll supply them when someone points out what I've skipped.

Car is an 85 Z28 TPI/LB9

I had no spark, took the cap and rotor off, looked good. Took the coil out of the cap, the wires were screwed up. One had been pinched on install and was bare in spots, the other visibly had been arcing. So, I took the ignition module out as well and off to the parts store I go.

For good measure, I bought a cap/rotor. They tested the ignition module (4 times), all good. And I bought a new coil to replace the one that was visibly bad. Put it all back together and the car fires right up. I mean, right up. It hasn't run since October and it didn't even hesitate. It ran for about 10 seconds.

So, back to the auto parts store I go, ignition module in hand. This time it fails the test the very first time. I buy new and happily head home. Install it, and the exact thing happens. So I quit for the day. For the next couple of weeks probably, until I have some time again.

My question of course is has anyone run into something like this. Is there something in my distributor base that could be shorting and killing the components that have gone bad? I called in help on this and someone double checked voltages for me and said all was well.

Many thanks for any thoughts on the matter. And please keep in mind I'm not a mechanic and I'm learning as I go. I may need the dumbed down version of some things.

 

Almost 100 views! No replies... Anyone have any ideas? Any drawback to replacing the distributor entirely? I would hate to waste the money and just fry another new part.

 

I have only seen this prob a handfull of times in the 18 years or so I been working on cars.

1 was due to someone doing a lot of arc welding on the car with out removing the battery cables.

1 turned out to be cause of bad ground wires. He burnt up 3 modules and we couldn't really find anything wrong. I noticed he only had 1 14 ga ground wire, so I added a few more larger grounds just to see, and he is still using that same module today, 8 years or so later. So I'm guessing that's what fixed it.

1 ended up being the wires on the pickup in the dist. moving as the mech. advance moved, the wires had a tiny crank that we didn't see on the bottom and as the moved the crack opened up and the wire was shorting out against the dist. body

 

Thanks for replying, I appreciate it. I wondered about ground, but didn't check yet. And a buddy of mine mentioned something similar to the wire shorting problem you mentioned. I'll let you know if any of this pans out once I get a chance to get back to it.

 

Your welcome. Glad I could at least shed alittle light on the subject for you.

Ok, cool deal. I am for sure interested in knowing the cause and cure because like I said it's an odd prob that you do not see very many times.

I tend to go over kill on my grounds. You can never have too many. I run a 1/0 gauge welding cable from battery neg to engine block, 8 ga. wire from battery neg to fender, braided ground straps from back of both heads to firewall, 2 ga. wire from block to K member, 14 ga. from transmission to crossmember.

 

So it was ground related. But not existing ones. The dist. coil was not grounded properly. The one that was taken out had the ground wire from the coil attached but did not have the ground strap that connects to the wire harness. I also broke my pick up coil taking it out and had to replace it. So not 100% sure which part fixed it. What I can't figure is how I could have driven the car 3000+ miles over two years without a ground strap on the distributor coil and suddenly it was the root of this problem.

Like I said in the original post, I'm not a mechanic and learning as I go. I appreciate your thoughts on the problem. It all seems less and less mysterious as I learn.

 

Wow, cool I am glad you got it figured out.

Can you post a picture of the old coil / ground wire? A lot of the aftermarket coils do not use the strap. They have a black ground wire coming out of center of coil the other end of that wire has a metal tab thing soldered to it. That metal tab thing pushes down into the dist. cap and your factory wiring harness plugs up into the dist. cap.

Stock or stock types had a short ground wire with ring term on it and a metal tab thing. The wire and metal tab thing both went under one of the coil hold down screws, metal tab thing sticks into dist. cap

 

Both the old coil and the replacement coil had what you describe as "stock or stock types". I'll snap a picture of the old one when I get home if I don't forget.

 

Took a while, but here is the pic.

 

Wow, that thing looks to be in bad shape. I'm not sure if it was a ground prob or if it was shorting to ground. The red wire being bare like that could have touched the coil body or one of the metal tabs.

Also the yellow wire looks pinched in a couple of spots

 

Yeah, when we saw that we thought for sure that was the root of the problem, then replaced that w/new and promptly fried the ICM. I put in the new pickup coil and the ground strap at the same time, so it could be either. Not sure I care. It runs and I'm happy about that!

 

I hear you man. That is all that really matters. It's fixed and running