NO fuel pump...

[Hozer 88GTConv]

Gents,
The car died at idle in the driveway today after running for 5 minutes. I noticed that I didn't hear the "whhrrrr" priming noise when I put the key into the ignition.
So, fuel pressure gauge confirmed no fuel pressure. No fuses blown. I swapped the fuel pump out, still no joy. I checked the inertia switch (that white toggle is a little loose, but its 20 years old this summer) and it died at idle. I also swapped the fuel pump relay under the drivers seat.
Still nothing...ideas?

Thanks in advance...

[johnwb]

Check the harness at the computer,I had a problem with that before ,It wasnt pushed in all the way,we hooked it while we were applying rust check.I have a wiring diagram that I can post if it is of any use.

[Hozer 88GTConv]

Okay, easy enough. Your wiring harness managed to back out? Wow, mine has a serious hold-down bolt, but I'll give the harness a wiggle and see if it is a loose connection at the PCM.
Thanks.

[Hozer 88GTConv]

Okay, I swapped fuel pump relays and now the pump runs continuously. I'm assuming I've got a short somewhere...does that make sense or does anyone else have any ideas before I drop the tank again.

Thanks

[Hozer 88GTConv]

I checked the orange/light blue wire at the fp relay for resistance. It was above 10k, so I'm thinking no short.
Anything else?

Thanks

[Hozer 88GTConv]

Update:
After checking relays, voltages, resistance, etc. I swapped my old speed density computer in to see if the car would act normally.
It did. It ran rough (because it's mass air now) so it looks like a bad eec-iv. Found a A9L for $100.
I'll let you know...

[USMC302]

The relay is wrong IMHO. I had the same thing happen a long time ago, had a guy at autozone sell me a new relay and it wouldn't turn off, brought it back and he said it was the same part number for some other vehicle so he thought it would be the same cause they showed out of stock on mine. Went down the road to Advanced Auto and got the right one, worked great. You said you swapped in the SD computer and it worked, maybe he gave you a relay for a SD 88 mustang, see if they have a different relay for an 89-93 stang.

Not going to cancel out the computer though either. I can't beleive our cars are going to be 20 years old.....

Hey have you ran it at the track yet with the new motor?

[Hozer 88GTConv]

yeah, I hear ya. I've got a handful of these relays. The guys at the Ford dealership said the same thing about some being interchangeable. I've got my doubts...
I can get my damn PMS pigtail seperated from the old computer. I've spent all day basically trashing it so it looks like I get to buy another one of those too...
joy.

[Hozer 88GTConv]

Swapped computer to an A9L. No luck. Fuel pump appears to be working, hear the priming noise and I smell fuel, but the mechanical indicator on the schrader valve indicates NO pressure at all.
I installed a new FPR and still NO fuel pressure, but I smell gas.
I installed two new relays from Ford at the ECM and Fuel pump relay.

Question: I have a FMS mass air conversion, originally had a A3M computer. Is there a chance the A9L is not compatible?
I actually got it to fire with the original speed density computer earlier, but it obviously ran like crap.
But it won't even manage that with the A9L.

I'm beat after working on it all day.
Thanks. Time for beer.

[USMC302]

Ok so wait, you put the SD computer in and it started, meaning you had some pressure in the lines at the schrader valve, but with the A9L, you had no pressure at the valve? If the pump is coming on with both computers, you should still see pressure at the valve. Pull a plug after trying to fire it with the A9L computer, are they wet with fuel or dry? When you swapped the fuel pump out, did you put in a new stock one, used stock one, used aftermarket...etc..? I think I remember cutting or modifying one wire on the ECU harness for my mass air swap, but can't remember which. I'll do a search to see if I can find it.

[USMC302]

You made sure you got the right computer for the right tranny? A few people mentioned before they put in the wrong computer, ( auto in a t5 or vice versa )and it fried a couple things.

[Hozer 88GTConv]

Thanks, USMC.
The fuel pump was a used one I had that was working before I removed it sometime ago.
My immediate concern is the lack of indicated fuel pressure on the gauge attached to the fuel rail. I'm going to open up the fpr and see if that's it. In my haste last night installing it, I didn't adjust it any. So maybe it's closed, but that's pure hope right there.
I'll also check the plugs. If they are dry, guess I'll be dropping the tank again and verifying power is getting to it first, then replacing the fuel pump.

I'm going to call around too about the computer compatability. My understanding from reading around the net is that A9L's, A9P, A3M, X3Z, yatta, yatta, are all interchangeable, regardless of transmisssion.

I'll keep you posted, thanks for your input.

[Dark_5.0]

You dont think the hose that goes on the pump could have cracked or came off do you?

[Hozer 88GTConv]

Dark,
Thanks for asking. I've primed it over a dozen times, so my guess is that there'd be fuel somewhere on the chassis and ground if that was the case.
I think I'm going to go with another new 225lph bbk pump. It's an expensive way to troubleshoot. But I just installed a new Kirban FPR, so that's not it.
I'll naturallly check the lines when I drop the tank and the fuel filter is only a year or so old...
I'll let you know...

[Dark_5.0]

Originally Posted by Hozer 88GTConv

Dark,
Thanks for asking. I've primed it over a dozen times, so my guess is that there'd be fuel somewhere on the chassis and ground if that was the case.
I think I'm going to go with another new 225lph bbk pump. It's an expensive way to troubleshoot. But I just installed a new Kirban FPR, so that's not it.
I'll naturallly check the lines when I drop the tank and the fuel filter is only a year or so old...
I'll let you know...

No I am talking about the hose that goes on the fuel pump inside the tank.

I had mine crack once and it wouldnt build pressure.

[Hozer 88GTConv]

Dark,
Disregard my last, I've been drinking again! I will absolutely investigate the hose while I've got the tank down.
Cheers

[Hozer 88GTConv]

Update:
Back at it again...I'm not showing any power getting to the fuel pump wires at the tank.
Which wire is the hot one at the relay under the seat?

I'm going to check there for 12v then move on. The tank is off and the pump is hanging out for troubleshooting.
I'm not going to bed until I figure this out tonight.

No beer either so I had better figure this out.

[Hozer 88GTConv]

The red/black wire to the relay under the driver's seat shows 11.8 vdc. I'd like to test the output, but don't know which one to pierce.

I have 4 of these advance auto parts relays, can they all be bad?

Does anyone have the wiring diagram? I'm thinking the relay itself, because there is no power on the red wire at the fuel pump.

Reminder: The car was idling fine in my driveway when it just stopped. So, I doubt it was the inertia switch crapping out.

thanks...

[Hozer 88GTConv]

I've got 12v at the inertia switch red wire too.
should the red black have 12v also back to the fuel pump relay?

I can feel the fp relay actuate under the seat when the keys are turned so it seems to be working.

It's still dead at the fuel pump connector...hmmm

[johnwb]

The relay can still turn on without supplying power to the pump.I have a diagram that helped me before,follow the black/orange wire back to the blue wire with fuseible link at the starter solenoid.This is the power wire to the computer that supplys the relay to power the pump,hope you can make some sense of that,lol.