fuel issues

[sidewayzisbest]

Well anyone have an idea got my car back together and fuel pump wouldn't get any power. I changed fuel pumps and that didn't work. I went to check that relay underneath the seat and had a wire going to the 2 power prongs in the relay and the fuel pump cut on(didn't make any fuel psi though =x). So i thought it was just the relay i got the new relay and nothing is happening. Any thoughts?

 

[HISSIN50]

what wires have what happening on the FP relay? should be control 12 volts, control (from puter ground), constant 12 volts from fusible link by starter relay and output of power feed to the pump. if you have those, i would check the wiring at the pump - see if there is an open on the way back.
i might also check the fusible link to ensure it is not half burned (flowing some volts, but not decent amps).

good luck.

 

[HISSIN50]

i just looked at that post - i should not type and eat a sandwich. i figure you know what i mean, but if not lemme know and i will clean the post up.

good luck.

 

[sidewayzisbest]

well it made fuel pressure now that battery charged but still wont do it without bypassing the relay

 

[sidewayzisbest]

what wires have what happening on the FP relay? should be control 12 volts, control (from puter ground), constant 12 volts from fusible link by starter relay and output of power feed to the pump. if you have those, i would check the wiring at the pump - see if there is an open on the way back.
i might also check the fusible link to ensure it is not half burned (flowing some volts, but not decent amps).

good luck.

Well the relay has 4 prongs on it. I found the pink/black strip and the red one are the 12 volt source and the acc. That works when i touch the 2, im not sure which one is ground. I bypassed the fuse link since that looked like it was burnt for some reason and replaced it with another 12ga fuselink.

So since it works when i bypass the relay i would assume it has to do with the other 2 wires on the relay. Im guessing ones a ground and the other is a ignition switch. Anyone know where the ground leads to or which fuse it would be for the "ignition on switch" thanks

any other relays or anything could be it?

 

[sidewayzisbest]

well i cut the coating on the green wire ( 1 of the 2 smaller ones)so i could see if its something that was cut where it wouldn't come on with the ignition. And it did turn on but didn't turn off. Like when the fuel pump primes then stops it just doesn't stop. Is this ok? what do i need to do? thanks

 

[HISSIN50]

ok, the schematic i am lookin at is for an 88, so i dont know if wire colors changed.

on an 88, you would have:
red/blk: 12 volts with the key on (low amp relay positive trigger).

tan/lt grn: ground from the puter. only happens when the key is on. it is a ground and wont show up using the DC volts setting on a DMM.

orange/lt blue: power feed for the pump. it comes from the link (which should be 18 gauge, i think) on the solenoid. should be hot at all times.

pink/blk: feed to pump. only hot when the relay energizes.

if your FP relay latched (stayed on), i would probe wires again to see if all the wires are active (if not, the relay may be at fault). another cause of a FP that wont shut off is a bad EEC relay. there would be other symptoms though.


here is info on the link size - i could be wrong (see bottom right corner for link sizes):
http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif

and another of Tom's diagrams for the FP relay (see the top left quadrant for the relay and its wiring):

http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

I WOULD DOUBLE CHECK THE COLORS AND FUNCTIONS - I DID THIS QUICKLY AND COULD HAVE HAD A BRAINFART WHILE LOOKING AND TYPING.

good luck.

 

[sidewayzisbest]

thanks im trying to look over it right now, so it prob be a bad idea to have a wire on the green to a fuse to keep it running? And about the EEC relay , i havent started my car in a while cuz i had to pull motor out. Is there any way i can check that and about where do u know thats located


thanks for all the help hissin50

 

[sidewayzisbest]

eek the 91 must be different the pink one is the one from the silenoid. But i know this is a long shot but does anyone know what a yellow wire is that hangs with the plug to the starter coil. I was thinkin that was the fuel pump since that one was the one that burnt up but cant seem to figure out what it is. thanks

 

[sidewayzisbest]

n/m very bad discreption but im thinknig thats the wire from the eec computer and relay. Anyone know where the relay is at?

 

[HISSIN50]

The EEC relay is above the puter in the pass kick panel. if one can run the diagnostic tests, i think that means the relay is alright (lots of stuff will not work if the relay is not engaging).

you might try Autozone's site for schematics for your 91 - i think they go year by year.
i would write down each wire color and check them cold (key off) and then warm (key on) and note each reading. you might be able do deduce what you are missing.

good luck.
good luck.

 

[sidewayzisbest]

this might be a dumb question but im really cant figure this thing out and it is driving me crazy past no end.

What if i splice a wire into the wire that goes to the eec to a fuse that only on when ignition/run. It seem to work then even though it was loud (but then again this is my old stock pump so it was kinda of like that anyways my walbro wont be here since its on"backorder")

 

[HISSIN50]

this might be a dumb question but im really cant figure this thing out and it is driving me crazy past no end.

What if i splice a wire into the wire that goes to the eec to a fuse that only on when ignition/run. It seem to work then even though it was loud (but then again this is my old stock pump so it was kinda of like that anyways my walbro wont be here since its on"backorder")

IMHO, not a good idea. i would find the problem and fix it.
good luck.

 

[sidewayzisbest]

Any ideas how i could check the 2 wires going to the computer?

i hate eletrical stuff


the fuel pump wire and fuse link seem to be fine(other post i made i acutally spliced in the fuelpump wire to the fuse so that was bypassing everything but least i know it works)

 

[HISSIN50]

Any ideas how i could check the 2 wires going to the computer?

there should only be one wire from the puter to the FP relay (it is the control ground for the relay).

if you permanently spliced something, all bets are off. what did you do exactly? did you rig it so the pump comes on with the key (bypassing the puter switching it on and off)?

for diagnostics, one can jumper the self test connector to engage the pump (future FYI).

good luck.

 

[sidewayzisbest]

there should only be one wire from the puter to the FP relay (it is the control ground for the relay).

if you permanently spliced something, all bets are off. what did you do exactly? did you rig it so the pump comes on with the key (bypassing the puter switching it on and off)?

for diagnostics, one can jumper the self test connector to engage the pump (future FYI).

good luck.

But doesn't one of the wires go to the inertia switch and then to everything(maf/iac/) then goes to the "power relay" in the EEC

But what you mean all bets are off? I just rigged it to where it comes on with the key just to make sure the fuelpump and that wire is working(after i replaced the relay). Did that mess something up? I just dont see why the relay not working if its getting power and the pump works.

If it would't mess anything up does the computer control what speed the pump flow doing different rpm? B/c i really need to get this thing running to go to school tomorow.

thanks

 

[sidewayzisbest]

Well i let my friend talk me into just wiring another relay and have a switch for it, like an external pump. Im going to have to do that anyways if i get his turbo.

 

[HISSIN50]

But doesn't one of the wires go to the inertia switch and then to everything(maf/iac/) then goes to the "power relay" in the EEC

But what you mean all bets are off? I just rigged it to where it comes on with the key just to make sure the fuelpump and that wire is working(after i replaced the relay). Did that mess something up? I just dont see why the relay not working if its getting power and the pump works.

If it would't mess anything up does the computer control what speed the pump flow doing different rpm? B/c i really need to get this thing running to go to school tomorow.

thanks

sorry for the confusion. when i said all bets are off, i was referring to me not knowing how you had the wires configured now. so unless you were very specific, i would not know what had been done.

as for messing something up, again, not knowing exactly what was done, we have no idea. it sounds like you know what you are doing and are fine though. (i might have just used a fuse to jump the common and N/O terminals on the relay to see if the pump primed).

you are right, the 12 volt control side of the relay does come from the puter, but there is no puter control (half the wiring in the car comes from the puter too). i dont consider it a computer function as the puter has no input.

I'm no Jrichker, but as far as i know, the pump sees the same voltage as the rest of the system. (hence our pumps really are variable in their ouput, depending upon how much voltage it sees).

i would just use sound wiring to try to ensure the car does not die while driving.
good luck.