The Neverending GMC Repair

[Marcos Beltran]

So I have a 96 gmc 4.3 V band this truck wont run more than 2 weeks before it breaks down again. Well this last time was for 2 days before it broke down. I bought the truck maybe 2 to 3 months ago. Replaced fuel pump, FPR, cleaned fuel injectors, replaced spark plugs/wires, cleaned dist cap, cleaned egr valve, maf sensor, cleaned and flushed radiator, new thermostat, new brake switch, and im pretty sure there are other parts im forgetting. I always got the P0171 and P0174 codes, i intermittently got a MAF sensor code, brake swtich code, and O2 sensor code( only one time). My last repair had me chasing down down some fuel issue gremlins. I was getting crazy long term fuel trims of 25 plus. Well got that all sorted out and truck was running like a champ. Actually the best its ever run. Was getting near perfect fuel trim readings for 2 days. Then on the 3rd day i noticed it was a little off when idling. So i put the scanner on it and was getting between 7 and 9 on the long term fuel trims. Took it around the block a few times and finally the dreaded bog came back. So it ran after the 1st bog and then the second time the truck died and i couldnt turn it back on. Been sitting in my driveway the last 2 days. From the symptoms now it seems like the ignition control module maybe going or gone out. Cranks but wont turn over. This was my sons truck but i dont trust it anymore. Its always broke down on him and left him stranded on the Hwy once already. Think im gonna take over this one and give him mine. During the last repair all the codes cleared and finally for the first time i got a green check across the board for all the systems. I thought well damn i finally fixed this damn truck but it didnt last. So do these ignitions modules just go out with no warning cause it sure as hell didnt give me one and will it cause the truck to bog down the way it did? Will it also kind of drag at first similar to a bad starter cause it does that every once and a while when trying to crank it . Oh it also has a new battery.

 

[red98]

So I have a 96 gmc 4.3 V band this truck wont run more than 2 weeks before it breaks down again. Well this last time was for 2 days before it broke down. I bought the truck maybe 2 to 3 months ago. Replaced fuel pump, FPR, cleaned fuel injectors, replaced spark plugs/wires, cleaned dist cap, cleaned egr valve, maf sensor, cleaned and flushed radiator, new thermostat, new brake switch, and im pretty sure there are other parts im forgetting. I always got the P0171 and P0174 codes, i intermittently got a MAF sensor code, brake swtich code, and O2 sensor code( only one time). My last repair had me chasing down down some fuel issue gremlins. I was getting crazy long term fuel trims of 25 plus. Well got that all sorted out and truck was running like a champ. Actually the best its ever run. Was getting near perfect fuel trim readings for 2 days. Then on the 3rd day i noticed it was a little off when idling. So i put the scanner on it and was getting between 7 and 9 on the long term fuel trims. Took it around the block a few times and finally the dreaded bog came back. So it ran after the 1st bog and then the second time the truck died and i couldnt turn it back on. Been sitting in my driveway the last 2 days. From the symptoms now it seems like the ignition control module maybe going or gone out. Cranks but wont turn over. This was my sons truck but i dont trust it anymore. Its always broke down on him and left him stranded on the Hwy once already. Think im gonna take over this one and give him mine. During the last repair all the codes cleared and finally for the first time i got a green check across the board for all the systems. I thought well damn i finally fixed this damn truck but it didnt last. So do these ignitions modules just go out with no warning cause it sure as hell didnt give me one and will it cause the truck to bog down the way it did? Will it also kind of drag at first similar to a bad starter cause it does that every once and a while when trying to crank it . Oh it also has a new battery.

The ICMs do just crap out, especially aftermarket ones, keep a spare in the glovebox.

My truck bogged down 3/4 the way up a bridge, was making just enough power to basically rev up to 2k rpm and sit still on the bridge, but not enough to turn the wheels, then the motor died and I started rolling, had to throw it in R and weave my way down the bridge thru traffic backwards, and jump it over curb into a Les Schwab parking lot that was nearby. It was the ICM, I smoked my starter while diagnosing it, so I ended up doing new ICM, cap, rotor, starter, and battery/starter cables. It would try its damndest to start, but would not, and eventually stopped trying to as well. I'd get a high quality aftermarket one, and a low quality cheapo one and install the good one, keep the cheapo in the glovebox for next time.

 

[Marcos Beltran]

Well its not the ICM. Just put a spark tester between plug and wire and getting plenty of spark.

 

[Erik the Awful]

When my ICM went out, it ran fine until you put a load on it. The only way to truly test an ICM is to replace it with a known good one.

 

[Marcos Beltran]

When my ICM went out, it ran fine until you put a load on it. The only way to truly test an ICM is to replace it with a known good one.

Its the d*** fuel pump!!! After I tested for spark and ruled that out i figured what the hell i still have the fuel gauge rented from autozone let me test it real quick. Sure enough when turning the key it only goes up to 38 psi , very slowly. Man i literally replaced that pump twice already. Once just cause the truck was sitting for over 2 years and the other time last weekend cause i was suspecting the check valve went bad. Im starting to think this truck is cursed!!!

 

[Erik the Awful]

If you need motivational inspiration, feel free to read through my Way Cool Jr. build thread. My $1000 truck needed everything. I did put the cheapest no-name Vortec-style fuel pump in it I could find, but after reading everyone else's horror stories, I'll replace it with an AC Delco when it goes out.

More Information for GM GENUINE EP381

 

[kenh]

A perfect case to buy "lifetime" warranty parts. I warrantied 4 ICM's from Advance auto. Took that many and a trip to the treasure yard to get a genuine GM coil to replace the Accel coil installed by the PO.

Ken

 

[Marcos Beltran]

If you need motivational inspiration, feel free to read through my Way Cool Jr. build thread. My $1000 truck needed everything. I did put the cheapest no-name Vortec-style fuel pump in it I could find, but after reading everyone else's horror stories, I'll replace it with an AC Delco when it goes out.

More Information for GM GENUINE EP381

Replaced it with a Delphi pump from autozone. Supposed to be a good brand right?

 

[BPR Speed]

How's your fuel tank look inside? It may be smoking fuel pumps due to clogging the pick up sock at the pump. 2 years of sitting can cause problems later on down the road.

 

[Marcos Beltran]

How's your fuel tank look inside? It may be smoking fuel pumps due to clogging the pick up sock at the pump. 2 years of sitting can cause problems later on down the road.

Its clean.