Question about 1988 Ford F 150

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Why do i have to bypass my fuel pump relay

I went ahead and ran a bunch of test on my fuel pump.I had a bunch of trouble after I installed new engine.I jumped my fuel pump relay and my fuel pumps finally came on.I dont understand why I have to bypass it.I bought a new fuel pump relay and it still wont provide power to the pump when I switch the key to run.I need to know where to start.Which grounds should I check and what test should i run.Where is the fuel pump relay ground locater.What would cause that relay no to click over and transfer the power.Something in my ignition that the relay is not detecting.The relay should detect a signal from my ignition key that tells it to give the power from the hot wire to the inertia switch.Why isnt it detecting the signal?

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  • Ford Master
  • 5,056 Answers

I look at the relay as two different circuits, the load side of relay is that line with arrowhead, when relay is energized that line moves to other terminal, you can see voltage to load side of relay comes from fusible link. That circuit goes through inertia switch, then to the pump. Then you have the control side of relay, left side in the diagram, that side has to have voltage and ground, voltage comes from eec power relay and that circuit is grounded by the pcm.
why do i have to bypass my fuel pump relay - f150 fuel pump-zkue20ih5gqqvta5qpd2pmol-4-0.jpg

Posted on Mar 25, 2017

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6ya6ya
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Posted on Jan 02, 2017

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subytech1
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SOURCE: my 98 windstar gl is not getting the ground comand

If you don't think your getting the ground command through your PCM, you can make your own ground just by bypassing the PCM all together. First you need to find a PCM connector end view showing which pins are which wires and locate the ground you need for that circuit. Then you need enough wire to loosely run from your battery negative terminal to the PCM connector. I you can back probe the PCM ground wire with a sewing needle and wrap the new wire around it, and attach the other end to the batt. neg. your just allowing the PCM to get it's ground another way. If it still doesn't start, try swapping fuel pump relays w/ a head light relay or one w/ the same part number on it. If you can't find one, just hot wire the pump relay again just to see if it starts and runs. If it does start and run you'll need to go to a wrecking yard and pick up a used PCM and maybe buy a relay for the fuel pump. I sincerely hope this info helps in some way.
subytech1...

Posted on Aug 07, 2009

  • 1 Answer

SOURCE: MY 2003 FORD EXPEDTION STARTS UP YOU DRIVE FOR

Had a similar problem was the air intake idle control motor

Posted on Aug 21, 2009

  • 1 Answer

SOURCE: no power to fuel pump or fuel pump wiring harness...

try the electrical ignition switch on the steering wheel colum

Posted on Aug 25, 2009

clifford224
  • 1975 Answers

SOURCE: 2000 ford mustang 3.8 no power at fuel pump fuse is good relay is good it does have a anti theft device, inertia is good

You have a fuel pu,p driver module that gets the power from the inertia switch and the power for the fuel pump comes from that module. I would start by checking for a wiring problem. Below is a picture of where that module is located. At the plug of the module you want to make sure you have good continuity from the pink and black wire at the module to the inertia switch. Then you will want to make sure you have continuity from the fuel pump to the module in the brown and pink wire. That should be the power source to the fuel pump. One other thing to keep in mind and that is the PCM controls ground to the fuel pump so this may be an issue. Try that first to see if you have a wiring problem. If you have power from the inertia to the module but no power coming out of it to the fuel pump this may be your problem. Hope I was able to help...

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Posted on Feb 29, 2012

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