Ive been havin a helluva time diagnosing why my fuel pump on my 97 F-250 HD gas will not work. The truck came with two tanks, but I eliminated the front tank 3 years ago (rotted and leaking), and replaced the rear tank/pump at the same time. Started by assuming, on bad advice, to replace the rear fuel pump yesterday.
Well, long story short, it still doesnt work. I then replaced the relay, but am still just getting a click instead of a humm, when cycling the key. Ive double checked the inertial switch on the passenger side kick panel, and thats depressed.
I figured I'd attach this post to this thread seeing as it was already discussing the fuse box in the engine compartment. Any ideas on where to go from here and how to properly test the relay box and fuel pump harness?
First of all I take it you have an OBD-I EEC-IV system.
If so just ground pin #6 of the self-test plug, turn on the key and see if the fuel pumps run.
If they do not then go to the inertial switch on the passenger side kick panel and check for voltage with a load type test light. A volt meter will not work here as it will say there is voltage when there is not.
If the fuel pump do run when you ground pin #6 of the self-test plug and turn on the key you may have a bad PCM Computer. But short pin #2 to pin #6 of the of the self-test plug, turn on the key and see if the fuel pumps still run.
If they do not then you have a ground problem coming from the body ground to pin #40 & #60 of the PCM Computer.
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