Will crank and run on ether but will not pump fuel. Replaced the side tank fuel pump and and filter tested the relay by changing it with the horn one and both seem to work. Tried bypassing using Test port jumper checked fuses and made sure the inertia switch was not set off.

checked the wiring to it and it seems fine. Cannot figure out why it will not start nor pressurize fuel rail.

My next steps
-replace/test relays
-check lines for clogs ( I didnt bother doing it before because the fuel tank looks spotless inside.
-electrical test new fuel pump to see if defective
-test tank selector (I assumed this was ok becuase fuel gauge switched to show both levels in tanks.)

I am fixing this for a friend of mine it was her grandpas truck we got a crappy haynes manual.

if you have better wiring diagram it will be very helpful and I would be very grateful.

 

Check the ECM and Stator.

 

Stator on the starter?

 

Pull the ECU and take the lid off, look for leaking capacitors. If it runs on ether the ignition system should be fine and there should be an initial firing of injectors when the key is turned on.

 

If your bypass was grounding pin #6 of the self-test plug (VIP Data Link) and turning on the key then forget the ECU (PCM) for now.
If you shorted pin#2 to #6 of the self-test plug and turning on the key and the selected pump did not run you may not have a ground to the computer.

The selector switch may still be the problem as the gauge and pump wiring are two separate systems and use different contacts inside the switch.



A bad fuel selector switch that will work the fuel gauge OK but not the fuel pump:


The fuel pump wiring drawn a different way.


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Thank you for the help I will be sure to try this out.