Ignition Module keeps getting fried - Need Ideas o

[fd59]

I am having problems with the ignition system in my 1990 model Isuzu Trooper with a GM 2.8L v6 265,000 miles.

On Christmas Day the the truck stopped firing while going down the road. I had a gut feeling that the ignition module had gone bad so I replaced it the next day and was back on the road again. At least for a couple or three weeks until I was going down the road about a half mile from my house when my Trooper instantly started running like crap. I knew that if I stopped the truck that it wouldn't start again. I was able to make it to the house. The truck would barely run, had no power and was backfiring. After it quit I could not get it started again. I figured it was the ignition module again, but I had it tested and it passed using two different analyzers. Then I figured that the timing chain had jumped time and when I tested the the play it had nearly 10deg of play, so I replaced the timing chain. After replacing the timing chain the Trooper would start and run for about 5 - 10 minutes and then start backfiring and wouldn't start until it cooled down. Tonight I went and had the ignition module tested again. This time it failed, so they replaced it. After installing the new module the engine ran fair. I let it idle for about 15 minutes and started down the street. Within a couple of blocks the engine stopped cold - now the third ignition module fried.

I am out of ideas here. Does anyone have any ideas as to why the ignition module keep burning up?

Any help is appreciated.

Thanks

Mack

[bszopi]

I kept burning up ignition modules in my old 73 Chevelle 400SBC, but that was like 13 years ago, so I can't remember what the issue ended up being. But I do remember being in the same boat... It seemed every few months I was burning up the module. We finally figured it out after 3-4 modules. If I can remember what it was, I'll toss the idea out there. In the mean time, I'd look for any loose wires or anything that might be shorting out the module.

[IsaacHayes]

Are you sure they are fried? I've replaced the ICM a bunch of times and everytime it ended up being the CPS sensor.

[bszopi]

I'm pretty sure the module he is referring to is the module inside the distributor.

[tractorman]

.

It might not be your ignition modules. Sometimes electrical parts can quit working intermittantly, then start working again- maybe once they've cooled down. The pickup coil and ignition coil are both a possibility. If you're quite sure that the engine IS in fact burning out modules, then take a look at the rest of the ignition system. Bad plugs, wires, distributor cap, etc. can take out a coil or module. For that matter, a bad coil could probably also take out a module, though I don't know that I've ever seen it.

I think you're just going to have to throw parts at it.

[fd59]

Well, I found the culprit..... What’s that saying about when we ass-u-me something?

Well... Monday, when I put the new Ignition module on and the Trooper only went a couple of blocks before the engine quit I "assumed" that I had just fried another module. It was almost midnight so I decided I would quit for the night and solicit suggestions for solutions to my problem on the forum the next day. (BTW-Some excellent advice was given! Thanks) Tuesday night I had our monthly FD training. So I was finally able to "tackle" the Trooper last night about 10PM.

First, I tried to crank the truck in hopes that there may have been some divine intervention by God to help me out. But, that was not the case. Then, when I got under the hood I realized something... I did not smell any gas fumes and the throttle body had no residual gas in it from when I just tried to crank the engine. I then connected a timing light to see if I was getting fire and lo-and-behold bam!!!! The engine was firing!! I hadn't fried the module after all. Now I was getting excited. "We're making progress!" I decided to check for any trouble codes, but none showed up. I had another "gut" feeling that I had fuel pressure, but for some reason the injectors were not getting the signal to open up. So, off comes the distributor cap to check the ignition module again. As soon as I lift the distributor cap "POW!" the problem hits me right between the eyes! The lash time I attached the distributor cap I pinched the injector signal wire between the cap and the distributor. I fixed that problem and was running again, but still not running right..... It would just barely idle and had no power. I still had the timing light attached so I checked the timing..... It was firing about 15deg After TDC. I spent the next 1/2 hour or so trying to get the bolt loose that holds in the distributor. This was a major pain! Who ever designed that mechanism for holding in the distributor on GM engines should be shot! But, I finally got it. I set the time to 10deg before TDC and went for a 15 min drive around 1am. The engine is running better that it has in the last couple of years.

Thanks for all the help!

[bszopi]

Well, glad that everything worked out and you didn't even have to spend any money to fix the problem!

[CNCguy]

Well, I found the culprit..... I still had the timing light attached so I checked the timing..... It was firing about 15deg After TDC.

Sounds like there may be a lot of timing chain/gear wear. You may want to check it out before it slips on you.

[fd59]

Sounds like there may be a lot of timing chain/gear wear. You may want to check it out before it slips on you.

I replaced it and the timing gears two weeks ago. Everything is running great now.