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I am not getting any action from my fuel pump after my swap. when i turn the key on, it doesn't do anything. but, if i jump the wires at the relay, the pump powers up.
Does this mean I have a bad relay?
BTW... My fuel gauge goes way past the full mark and my oil pressure gauge isn't plugged in.
First thing check grounds and relays.
Couldn't find any open grounds so I should be good on that.
I was checking the voltage at the relay and had just under 12v at the positives. But the ground showed around 8v. I know that can't be right.
Use a " known good ground " i.e. battery, frame, under hood grounding tab, accessory bracket, etc.... then test all the (+) again, if you are getting power when checking the (+) with a (-) from the harness there is the possibility that a wire is rubbing against another wire. Try this as well get a volt meter and clamp the black wire to the neg. battery and use a jumper and connect the pos. wire to a different ground lug ( back of motor, back of firewall, etc... anywhere there is another ground terminal ) if you are getting (+) from any other grounds, trace the wires back and find where they are rubbing though and touching the bare metal
Thanks Mr HP. Ill try that this evening and post the results.
Ok. here is what I have come up with... I decided to snip the strange blk /wht ground wire that has power and ground the relay to the frame. And when I turned the key on.... BAM we have a working fuel pump!!!! Buuutttt... when I went to start it, I wont crank anymore. So I re-connected the wire and it will crank, but no fuel pump.
So, I decided to chase the black wire to see where it goes. It went to a bundle of other blk/wht grounds so I'm stumped.
I also found that the red wire (relay pin #87a) has a black plug on the end of it that was sticking out of the wire loom. I don't see any other single wires that could go into it. What the hell is this for? Am I supposed to put power to it?
Here are pics of the mysterious red wire and the bundle of grounds. Also a generic diagram of the wires in the fuel pump relay.
Attachment 7826
Attachment 7825
Attachment 7827
So I solved the problem, it was really simple. I grounded that set of grounds to the coil bracket on the valve cover. Apparently, this is a bad idea. I moved the ground to the alternator bracket and my gauge started working and the pump kicks on. I still sdont know why my test light was showing voltage....
Now, my truck would crank over BEFORE i would ground the fuel pump relay. Now it won't crank. I had an issue where the PRNDL switch wasn't allowing it to crank. I bought a new one and it fixed that problem. Now since I fixed the fuel pump.... it wont crank again...