ICM

[77snowwheeler]

Was curious if anyone has had problems with the control module? I’m driving down the road, and just like that, my truck back fires and stalls. Turn the key off, and a minute later starts right up. Couple miles later? Same thing. At first I thought it was a gas problem, because my clear fuel filter shows a real small fuel stream. But I’ve had to change my ICM twice before within a year. I ordered an AC Delco coil and ICM. Hoping that’ll fix it?

 

[cheavyk10]

Sounds like you're getting low fuel pressure from your fuel pump. That clear filter should be all the way full. The ICMs either work or they don't.

 

[77snowwheeler]

The thing is, I check the fuel pressure about three months ago, when it was doing it, and the pressure was really good, and consistent. I put a new ICM and everything was working until now? The pump is a 4-7, and the pressure was 6,8.

 

[77snowwheeler]

And what weird is, last night I could get about two miles down the road after it dies, and today about three blocks. So something is gradually getting worse?

 

[Wes Harden]

You might have a split hose pre pump. I am making guesses here, you are running a carb, and have an electric pump outside the tank. Where is your pump ? I mounted mine on the tank skid plate as close to the bottom edge as I could with out hanging below. I had it higher at first, low middle, and starved for fuel up a 10% grade. Moved it down and driven that same hill several times no issues.

Be sure to use dielectric grease between the new module and the plate. Clean the old gunge stuff off 1st. Inspect the wires to the pickup coil, but be gentle, they get hard and crack. This could be your problem more so then the ICM if the pickup coil wires have an intermittent open. It could run like poor timing or spark jump, and stall.

 

[dyeager535]

If you are doing the ICM, you might as well try a complete distributor. Pickup coils seem to be reaching the end of their life span, mine from 1988 died a few years back, it seems to be a pretty common issue anymore.

Since you have to pull the distributor to get at it, and the parts alone often cost what a new distributor does, a complete replacement is an "easy fix". Either way, nice to have a complete known good spare.

 

[77snowwheeler]

You might have a split hose pre pump. I am making guesses here, you are running a carb, and have an electric pump outside the tank. Where is your pump ? I mounted mine on the tank skid plate as close to the bottom edge as I could with out hanging below. I had it higher at first, low middle, and starved for fuel up a 10% grade. Moved it down and driven that same hill several times no issues.

Be sure to use dielectric grease between the new module and the plate. Clean the old gunge stuff off 1st. Inspect the wires to the pickup coil, but be gentle, they get hard and crack. This could be your problem more so then the ICM if the pickup coil wires have an intermittent open. It could run like poor timing or spark jump, and stall.

Definitely will check those wires. Everything on this truck is new, but I’m finding out, I have to go back through and fix stuff. Very frustrating. Thanks

 

[77snowwheeler]

If you are doing the ICM, you might as well try a complete distributor. Pickup coils seem to be reaching the end of their life span, mine from 1988 died a few years back, it seems to be a pretty common issue anymore.

Since you have to pull the distributor to get at it, and the parts alone often cost what a new distributor does, a complete replacement is an "easy fix". Either way, nice to have a complete known good spare.

The distributor is new. I’ll check everything around it, hopefully it’s not a bad one. Thanks.

 

[Wes Harden]

If the dizzy is new the pick up coil should be in good shape.
Unfortunately there are some new distributors that aren't up to the task.
Good luck on this let us know what you find

 

[77snowwheeler]

I will thanks.

 

[ktmoutfront]

We have seen ICM do what you are describing. I have given a spare AC/Delco to 3 different people while out wheeling. Eventually it will die. I always carry a spare. I have not had one go bad. But the wires between the ICM and the coil fought me for months. Was frustrating, until I found it. Died going up hill or accelerating. One wire would not make contact inside the ICM plug, randomly. Found it while shaking the wires when the engine was running.

 

[cheavyk10]

I had the same issue as described above with my 93 S10. The hot wire from the coil to the ICM had a crack and it was grounding out on the intake manifold. I was having weird issues where it would cut out. Eventually the wire broke and I was stranded. It was an easy fix nonetheless.

 

[77snowwheeler]

We have seen ICM do what you are describing. I have given a spare AC/Delco to 3 different people while out wheeling. Eventually it will die. I always carry a spare. I have not had one go bad. But the wires between the ICM and the coil fought me for months. Was frustrating, until I found it. Died going up hill or accelerating. One wire would not make contact inside the ICM plug, randomly. Found it while shaking the wires when the engine was running.

Thanks a bunch for the info. I’m going to check all the wires closely. Replace the aftermarket stuff with AC Delco, put thermal paste rated up to 480F on the base plate, put vents on the hood to get rid of some of the heat. Put an inline fuel gauge in, so I can always see what that is doing. I’m getting a little tired of the craziness with this stuff. We go high in the mountains in deep snow. Don’t want to get caught with my pants down, lol. I’ll also check to make sure I didn’t wire something to that line, that could be raising the temp of the wire as well. I would bypass that ICM eventually if I could find a way to do it?

 

[dyeager535]

I wouldn't waste my time venting the hood. ICM's will go decades underhood IF things are working properly.

Venting also has the potential to screw up cooling actually. The fan does a good job of pushing the heat out of the engine bay as-is.