fuel pump problem

[1992MustangDW]

my fuel pump wont come on. So i took it out and tried it on a battery and it worked. replaced the relay under the driver seat. STILL NOTHING!

is there any kind of plug anywere that could be unplugged or any other problems that someone might have incountered?

[1992MustangDW]

going back out to check the brown use link by the starter solenoid.

[1992MustangDW]

ok so on my relay under the seat I have power to the orange and light blue wire, but no power to the pink and black wire that goes back to the fuel pump.

[ibstrokin]

Your fuel pump comes on for a couple of seconds when you turn the key forward , so if your testing, you need someone to keep turning the key on/off. There is a plug below the hood hinge in the engine bay on the dr side that has fuel pump wiring in it.

[facemelter71]

Also just for shits and giggles,check the fuel pump shutoff in the back by the taillights.

[1992MustangDW]

I checked it and it is ok, I have power to the eec, wich the fuel pump runs through it to tell it to turn on and off, i think I have a break in the wire somewere

[1992MustangDW]

If the motor is not grounded will the fuel pump still kick on?

[1992MustangDW]

I need Help with this please look at the diagram!!

The control path consists of the inertia switch, the computer, and the fuel pump relay coil. It turns the fuel pump relay on or off under computer control. The switched power (red wire) from the ECC relay goes to the inertia switch (red/black wire) then from the inertia switch to the relay coil and then from the relay coil to the computer (tan/ Lt green wire). The computer provides the ground path to complete the circuit. This ground causes the relay coil to energize and close the contacts for the power path. Keep in mind that you can have voltage to all the right places, but the computer must provide a ground. If there is no ground, the relay will not close the power contacts.

The power path picks up from a fuse link near the starter relay. Fuse links are like fuses, except they are pieces of wire and are made right into the wiring harness. The feed wire from the fuse link (orange/ light blue wire) goes to the fuel pump relay contacts. When the contacts close because the relay energizes, the power flows through the contacts to the fuel pump (light pink/black wire). The fuel pump has a black wire that supplies the ground to complete the circuit.

Remember that the computer does not source any power to actuators, relays
or injectors, but provides the ground necessary to complete the circuit. That
means one side of the circuit will always be hot, and the other side will go to
ground or below 1 volt as the computer switches on that circuit.



so there is four wires total to the fuel pump relay I have power to every single one except the pink and black wire to the fuel pump, does this mean my computer is bad and not providing the ground to close the circuit?

[1992MustangDW]

so i replaced the computer all relays and all the wires are good..

Anyone know of any grounds that trip the relay to come on or grounds for the computer?

[1992MustangDW]

so when i ground out the green and tan wire to the computer the eec relay buzzzzzzzzzzz like crazy, also when i turn the key on the relay doesnt click???

[quik lx]

I have seen this problem many times (2 in just the past 3 months). I first check the ground wire at the FP relay. If that is good, I make sure there is 12V on the Orange wire with a blue tracer (this tells you the fusible link in the engine bay is good). I then go to the EEC relay and find the wire that turns on the coil, cut it and splice in a wire and run it across to also power the Fuel pump relay coil. The car won't purge the fuel system anymore, but when are you gonna have the key in run and not want the engine running? The relay coils pull hardly any amperage and the EEC relay is fuse link protected anyway. This saves all the time of tracing out wires to find the bad splice because if the red wire on the MAF meter still has power you know its the splice and good luck finding those. Hope this helps.

[1992MustangDW]

well I found the ground and my fuel pump is working!!!!!


But when it primes it doesn't shut off..?? wtf is wrong with this thing

[quik lx]

That function is controlled inside the computer, it grounds the fuel pump relay for a couple seconds (2 or 3) until the computer gets a signal from the distributor TFI module saying the engine is running.

IMO If the car starts and runs....who cares if it dont prime, I know a few cars that do that and run fine.

[1992MustangDW]

alright. Im just going to leave it at that then... cant wait to drive it.