yj fuel pump problem

I dropped the tank to trace the wiring. Pump works when I supply 12v to the pump itself and fruther up the wire (inside drivers door) ( I lose the wiring after that ) but will not work when I turn the key on. I switched the relay for the working starter relay but still no pressure. Need help

What Year Is Your Jeep? Is Your Check Engine Light On When You Turn The Key In The On Position?may Not Have Anything To Do With Fuel Pump.

91 and the check engine light does not stay on for more than a second when you turn the key on

what is the problem? do you not have fuel presure?You can check the codes by turning the key in the on position (not all the way to run) then off three times (leaving it in the on position) and the light will start a sequence of blinks.It will start with a 12 which is 1 flash pause 2 flashes.It will do this three times then if there are any other codes stored it will flash them.You may not get any codes if it is a faulty fuel pump or short in the wire.If i can remember corectly 1 or two wires run to the fuse block under the hood to a relay.and another to the ignition switch in one way or another. May just be a bad relay,or a faulty pump

what is the problem? do you not have fuel presure?You can check the codes by turning the key in the on position (not all the way to run) then off three times and the light will start a sequence of blinks.It will start with a 12 which is 1 flash pause 2 flashes.It will do this three times then if there are any other codes stored it will flash them.You may not get any codes if it is a faulty fuel pump or short in the wire.If i can remember corectly 1 or two wires run to the fuse block under the hood to a relay.and another to the ignition switch in one way or another. May just be a bad relay,or a faulty pump
the wires run from ignition switch to fuel pump relay then to fuel pump.You may also have a auto shut down relay which is wired in with fuel pump relay.the relays are located under the hood next to the battery maybe in a black box.Im not to sure about the 91 yj.Something else you could try is switching a couple relays with each other to see if it is a relay problem.My 95 uses all the same ralays.