[88lowrider]

Originally Posted by ChevyTech

Clear the trouble codes that are in the ECM from you unplugging items like the Fuel pump relay. Then see if the system sets a trouble code the next time the vehicle won’t start or the next time it dies.

I can do this but I don't have a tester to test it with. Might be able to rent one as the I live in on the Olympic Peninsula of Washington - which seems to be a geographical oddity for parts stores. I have to drive two towns over to get to the nearest parts store or auto shop. There is a big rental place in the next town so it it happens again, I will try and let it cool down and try to start it again to get it home.
Last time out with the truck, it broke down, after waiting for the wife to come and get me, I was able to jump start it (battery was low from the last time me grinding away with the starter like an idiot)
After jumping it I was able to drive it home and Almost get it back to the spot were I drove away from that morning, It broke down in the driveway.
After waiting about 20 minutes, it started again but I had jumped the fuel pump relay - or, it was cooled off enough?


You are going to fight with this thing for a long time if you don’t use a logical plan to determine what the problem is. If you would test if power was getting to the fuel pump fuse under the hood When the ECM is sending the signal to prime the pump for a few seconds when the key is first turned on then we would have information that helps.

When it died the first time, I checked that fuse and there was no power to it.
I might have forgot to say that.
When you mention logical plan, it would be nice to know what this stuff does, how its supposed to work and when, that way I would have a clue on what is going on. Its really hard to find good information.

When I take it out in the morning, I have the light tester and tools with me so I will be able to check that right away.

No it does not shut off the fuel pump circuit. People think is does because they do not understand how the systems are interconnected.

The ECM controls the fuel pump relay.

The truck has a fuel pump relay that supplies power to the fuel pump when:
- Anytime the ECM receives a distributor reference pulse. (Engine running / engine cranking)
- The key is turned on engine not cranking – relay applied for 2 to 20 seconds (most trucks 2 seconds), depending on emissions equipment. Trucks over 8500 GVW and some other vehicles have and electronic Fuel timer module that allows the pump to run up to 20 seconds.
The key must be turned off for a certain amount of time before it will prime the system again when turned back on.

Remenber, there will only be power to the fuel pump for a few seconds when you first turn the key to the on position, so if you are turning the key on then walking around the vehicle testing for voltage to the fuel pump circuit there will be no voltage and should not be power to the pump.

The ECM should store a code 54 if the fuel pump relay fails.

I will see if I can rent a code reader and find out..

A bad module will not stop the ECM from sending power to the fuel pump relay for a few seconds when the key is first turned on.

A bad module will not stop the redundant circuit from supplying power to the fuel pump once the engine has oil pressure.

A bad module can cause the ECM the receive no distributor reference pulse during cranking, so after the prime timer has expired the fuel pump relay would not be energized.

Interesting....
Seems I messed up the Quote some how?
This might make it next to impossible to see my answers.

Thanks...
Joe