1996, 300K+
Helping a friend and read through search results for "crank no start", great info. Especially Romer's Emergency Troubleshooting Process....pure gold. I've never wished for a vehicle to just die and stay dead, at least long enough to go through the FSM procedures but this rig refuses to stay down for more than a few seconds/minutes.
History: Was chasing random knock sensor codes, forward unit I believe, and after splicing in new connector this issue disappeared. Drove the truck daily for a few weeks and it was running strong and steady. Zero Issues, no codes.
Driving one afternoon engine died and coasted to the side of the road, but restarted immediately. Ran fine. No codes.
Few days later, same thing but wouldn't restart immediately. Crank No Start. Waited 5-10 minutes, fired up ran fine. No codes.
Got it home, next day in the driveway cold start smooth idle. Wiggle Test wire harnesses at: Fuel pump, engine bay, etc, went for drive. Runs fine. Go home park it still at idle at operating temp, go under transmission and start wiggle test on some of the harnesses there. Nothing happens, still idling fine. Crawl out, stand up, turn to look at truck and.....it stumbles slightly and dies. Get in, and it cranks right up and settles in to it's normal smooth idle. We continue with wiggle testing under the ignition switch, all is well. 30 minutes later and it's still idling fine, laughing at us...teasing us....challenging us. Then it throws the knock sensor code we haven't seen for weeks. It was late, we went to bed.
So, being deprived of a any means to systematically diagnose this thing, we looked for any/all grounds, dodgy wires, chaffing, anything that could cause an intermittent electrical fault. When it dies, it sounds like it's running out of fuel, but hard to tell for sure.
Today we are installing a fuel pressure gauge to monitor while driving, next time it fails with any luck we'll see pressure fall off just prior if it's a fuel delivery issue. Fuel pump and Fuel Regulator are relatively new. EGR has been removed and capped. But again, when it runs it runs very, very well with no codes (except knock sensor code). It does only happen after engine is up to full operating temperature, never when cold or even warm so could be heat related.
Normally I don't through parts at vehicles, but I'm willing to make exceptions with intermittent electrical if within reason. Any suggestions on which components to replace blindly or other places to look for specific wiring degradation issues.
Thanks all, S.
Helping a friend and read through search results for "crank no start", great info. Especially Romer's Emergency Troubleshooting Process....pure gold. I've never wished for a vehicle to just die and stay dead, at least long enough to go through the FSM procedures but this rig refuses to stay down for more than a few seconds/minutes.
History: Was chasing random knock sensor codes, forward unit I believe, and after splicing in new connector this issue disappeared. Drove the truck daily for a few weeks and it was running strong and steady. Zero Issues, no codes.
Driving one afternoon engine died and coasted to the side of the road, but restarted immediately. Ran fine. No codes.
Few days later, same thing but wouldn't restart immediately. Crank No Start. Waited 5-10 minutes, fired up ran fine. No codes.
Got it home, next day in the driveway cold start smooth idle. Wiggle Test wire harnesses at: Fuel pump, engine bay, etc, went for drive. Runs fine. Go home park it still at idle at operating temp, go under transmission and start wiggle test on some of the harnesses there. Nothing happens, still idling fine. Crawl out, stand up, turn to look at truck and.....it stumbles slightly and dies. Get in, and it cranks right up and settles in to it's normal smooth idle. We continue with wiggle testing under the ignition switch, all is well. 30 minutes later and it's still idling fine, laughing at us...teasing us....challenging us. Then it throws the knock sensor code we haven't seen for weeks. It was late, we went to bed.
So, being deprived of a any means to systematically diagnose this thing, we looked for any/all grounds, dodgy wires, chaffing, anything that could cause an intermittent electrical fault. When it dies, it sounds like it's running out of fuel, but hard to tell for sure.
Today we are installing a fuel pressure gauge to monitor while driving, next time it fails with any luck we'll see pressure fall off just prior if it's a fuel delivery issue. Fuel pump and Fuel Regulator are relatively new. EGR has been removed and capped. But again, when it runs it runs very, very well with no codes (except knock sensor code). It does only happen after engine is up to full operating temperature, never when cold or even warm so could be heat related.
Normally I don't through parts at vehicles, but I'm willing to make exceptions with intermittent electrical if within reason. Any suggestions on which components to replace blindly or other places to look for specific wiring degradation issues.
Thanks all, S.