Hello, I'm posting this in the correct section this time.
I'm honestly at my wits end on this. I have a 1994 C1500 - 4.3L with a moving target type of issue. I'm hoping someone can help me as I've been throwing parts at this thing for quite some time. I'll give a rundown of the timeline and what I've done so far.
About two and a half years ago, I had a shop bag the truck. Ran completely fine after the bag job for about a year or so. The truck then started stranding me randomly. This is not my daily so it just gets driven on weekends and sparingly. The truck, engine wise, is completely stock 4.3L. I would get in the truck and take it to the gas station and would run perfectly. When I'd get back to the truck and try to crank, it would turn over but not start. This was the first time it had done this. My first idea was fuel pump relay. Ran to the parts store, purchased, installed and truck fired right up. The second instance was the next weekend-- same thing. Went to the store, came out and crank but no start. I thought maybe I had gotten a faulty relay-- went back to the parts store, exchanged, installed and no luck. After fidgeting with it for 30 minutes or so, cycling the key on and off, it finally showed little signs of life (coughing and sputtering). I put my foot all the way down on the gas pedal and she cranked. Drove it home, ran perfect. The next time, same thing-- cranked at home perfectly, ran fine down the road, wide open throttle-- no issues. Get to my destination and after being inside for a few minutes, no start.
The fuel pump is the original on the truck (truck has 200,*** miles). I figured it was time to be replaced. Bought a Delphi pump from RockAuto. Installed in the truck along with new plugs, wires, cap and rotor, ignition coil, fuel filter. After the install, it took about 30 minutes for the truck to crank fidgeting with cycling the key on and off and we could not hear the pump priming. Finally it cranked but was running terribly rich-- smoke coming out of the exhaust like straight fuel and the truck was acting like it was running on 3 of the 6 cylinders. We immediately killed it and installed the plugs and wires etc. Went to crank the truck again and it cranked and ran without issue. We thought this is what solved the problem.
Moving on, truck drove fine for a few months. Just as soon as I started trusting it again, I drive home one day and kill it in the driveway overnight to wash it the next day. Wake up the next day and crank but no start. At this point, I decided to install an ignition control module. After install, the truck cranked without issue. Drove it a few times and randomly it would crank but run terribly for about 15-20 seconds. Each time it does the running rich thing, it's duration is only 15-20 seconds and I have to feather the throttle to keep it running and then it immediately clears up. I have video of how poor it runs at first and then it just calms down out of no where and runs as it should.
The main issue is that the truck will either crank and run fine, crank but no start, or crank and run terrible for 15-20 seconds and then clear up. The issue is only on start, once the truck is running and going down the road, there are no issues, no check engine light, no other signs of any problems.
Still having this issue months forward, I start talking to mechanics and ask their opinion-- many of which aren't experts on OBD1 vehicles so it's more or less just throwing parts. I finally came to the conclusion that due to the moving target nature of my problem, maybe the ECM was bad. Purchased a used ECM with same PROM code and installed yesterday. Truck cranked and ran perfect. Killed and cranked it 15-20 times. Late last night I was celebrating my victory and had my neighbor over and was attempting to show off my victory and again----- crank and no start.
Throughout this entire debacle, I'm almost positive my issue is fuel. I can pour gas or starting fluid down the throttle body and truck will crank and immediately die unless pulsing the starting fluid. Like I said, any help would be greatly appreciated. I'm out of ideas.
I'm honestly at my wits end on this. I have a 1994 C1500 - 4.3L with a moving target type of issue. I'm hoping someone can help me as I've been throwing parts at this thing for quite some time. I'll give a rundown of the timeline and what I've done so far.
About two and a half years ago, I had a shop bag the truck. Ran completely fine after the bag job for about a year or so. The truck then started stranding me randomly. This is not my daily so it just gets driven on weekends and sparingly. The truck, engine wise, is completely stock 4.3L. I would get in the truck and take it to the gas station and would run perfectly. When I'd get back to the truck and try to crank, it would turn over but not start. This was the first time it had done this. My first idea was fuel pump relay. Ran to the parts store, purchased, installed and truck fired right up. The second instance was the next weekend-- same thing. Went to the store, came out and crank but no start. I thought maybe I had gotten a faulty relay-- went back to the parts store, exchanged, installed and no luck. After fidgeting with it for 30 minutes or so, cycling the key on and off, it finally showed little signs of life (coughing and sputtering). I put my foot all the way down on the gas pedal and she cranked. Drove it home, ran perfect. The next time, same thing-- cranked at home perfectly, ran fine down the road, wide open throttle-- no issues. Get to my destination and after being inside for a few minutes, no start.
The fuel pump is the original on the truck (truck has 200,*** miles). I figured it was time to be replaced. Bought a Delphi pump from RockAuto. Installed in the truck along with new plugs, wires, cap and rotor, ignition coil, fuel filter. After the install, it took about 30 minutes for the truck to crank fidgeting with cycling the key on and off and we could not hear the pump priming. Finally it cranked but was running terribly rich-- smoke coming out of the exhaust like straight fuel and the truck was acting like it was running on 3 of the 6 cylinders. We immediately killed it and installed the plugs and wires etc. Went to crank the truck again and it cranked and ran without issue. We thought this is what solved the problem.
Moving on, truck drove fine for a few months. Just as soon as I started trusting it again, I drive home one day and kill it in the driveway overnight to wash it the next day. Wake up the next day and crank but no start. At this point, I decided to install an ignition control module. After install, the truck cranked without issue. Drove it a few times and randomly it would crank but run terribly for about 15-20 seconds. Each time it does the running rich thing, it's duration is only 15-20 seconds and I have to feather the throttle to keep it running and then it immediately clears up. I have video of how poor it runs at first and then it just calms down out of no where and runs as it should.
The main issue is that the truck will either crank and run fine, crank but no start, or crank and run terrible for 15-20 seconds and then clear up. The issue is only on start, once the truck is running and going down the road, there are no issues, no check engine light, no other signs of any problems.
Still having this issue months forward, I start talking to mechanics and ask their opinion-- many of which aren't experts on OBD1 vehicles so it's more or less just throwing parts. I finally came to the conclusion that due to the moving target nature of my problem, maybe the ECM was bad. Purchased a used ECM with same PROM code and installed yesterday. Truck cranked and ran perfect. Killed and cranked it 15-20 times. Late last night I was celebrating my victory and had my neighbor over and was attempting to show off my victory and again----- crank and no start.
Throughout this entire debacle, I'm almost positive my issue is fuel. I can pour gas or starting fluid down the throttle body and truck will crank and immediately die unless pulsing the starting fluid. Like I said, any help would be greatly appreciated. I'm out of ideas.
