I have a 1995 K1500 Suburban and I have no signal/power to the side of the relay that put power to the fuel pump. I tested for that 2 sec/10 sec prime with a test light in the fuse/relay box on pin #87 but no light. I did the jumper test from #30 to #87 and the pump worked. By the diagrams I found online pin #85 comes from the PCM to energize the relay but no power there when key is turned on or when cranking?
Do I have a bad PCM or is there something else I can try before replacing the PCM?
Need help to solve this problem.

 

My guess would be bad PCM, I had the same problem and a new PCM fixed it. Figure out what caused it to get fried though in the first place. Mine was a wire I had running to a speed sensor on my transmission that had fallen onto the header tube, melted the insulation and shorted it out.

Test voltage going into the PCM to make sure it's getting power into it, then probe into the wires coming out of the PCM for the fuel pump power wires/trigger wire and check for spark as well.

 

I know you bypassed it with a jumper and got it to work already... But try another relay in there, just to be safe.

Also, bad ignition switches have also been known to cause issues just like you're describing.

Check for stored codes and clear them, just to be safe. I don't know about that year truck, but there could be a bad sensor or signal to the PCM from a bad OPSU or CSP sensor, etc, that's actually telling the PCM to disable the FP circuit.


I wouldn't rule out the PCM either... But I'm just giving you some other things to check first.