Engine Fuel not pumping

Creomod · Apr 13, 2026

Got a 89 coupe driving on hiway car shutting off I just swapped fp,fp filter,relay,regulator,car was running occasionally shutting off now won’t start back. Put key forward nothing on gauge what cannot be. O I also swapped the ignition switch . The interim switch is bypassed been that way for years I removed it and have the 2 wires connector together. Can a bad o2 sensor cause car not to start or fuel to prime to gauge? Maybe ecu getting bad signal or bad tps sensor cause this.

AeroCoupe · Apr 13, 2026

Have you checked for codes?

Noobz347 · Apr 13, 2026

Creomod said:
Can a bad o2 sensor cause car not to start or fuel to prime to gauge?

No

A bad PiP can keep it from starting. A bad TFI can too. Neither of those will stop the pump from priming.

Creomod · Apr 14, 2026

AeroCoupe said:
Have you checked for codes?

Yes got codes 85,18,31,41,29,63,95

AeroCoupe said:
Have you checked for codes?

Creomod · Apr 14, 2026

Noobz347 said:
No

A bad PiP can keep it from starting. A bad TFI can too. Neither of those will stop the pump from priming.

When I broke down side of road I checked immediately lifting hood turning key and looking at fuel gauge it don’t go up at all. I got in garage after being towed attempted again the pump made no sound. I just swapped the pump,distbutor,fuel filter,relay,regulator,ignition switch this past week & it’s been shutting off like that here and there. can ecu capacitor cause fp to work sometimes and sometimes not? I haven’t looked but when I get home today I’m gonna crack it . It’s been a few years scince I sent it to ecu exchange

AeroCoupe · Apr 14, 2026

A bad ECU can cause all kinds of problems.

I would try and force the pump to come on. You can do this through the diagnostic connector (what you connect the code reader to) under the hood. You want to install a jumper wire from the black/white wire to the tan/green wire. This will simulate the ECU grounding the fuel pump relay. If the pump comes on and you have good pressure then you either have a wiring issue or the ECU need a to be rebuilt.

Most send their ECU to get rebuilt here:

Ford Mustang 5.0 A9L A9P C3W A3M X3Z ECU Repair Service

Ford Mustang 5.0 A9L A9P C3W A3M X3Z ECUEngine Computer Repair ServicePlease fill out the R&R form here once you've placed your order.A Trusted Product with LIFETIME WARRANTY QUICK TURN AROUND TIMEDomestic and International Shipping available! Our Team is Available Monday - Friday 9am to 5pm...

www.theecuexchange.com

The codes you are getting are as follows:

Code 18 - SPOUT circuit open
Code 29 - No continuity in vehicle speed sensor circuit
Code 31 - Canister or EGR valve control system
Code 41 - Lean fuel mixture
Code 63 - Throttle position circuit
Code 85 - Canister purge circuit
Code 95 - Thermactor air diverter circuit

Some of these codes would make me check the salt and pepper shakers (black and white connectors) behind the back of the intakes.

Mustang5L5 · Apr 15, 2026

I think step #1 is to verify why the fuel pump isn't pumping. The other codes can wait.

Force the pump to run by jumping out the test plug. This bypasses the computer. If the pump still doesn't run, see if you have 12V power at the tank connector and if you do, replace the pump.

Creomod · Apr 15, 2026

Now out of no where the car started . Fuel going to gauge. Should I still force the pump to run or open ecu and do a visual ? My issue is my car drives the out of nowhere shuts off. Check fuel pressure,nothing , then it starts hours later. Mind you I just swapped the distbutor had nothing to do with fuel pressure,what can cause intermittent yes fuel pressure no fuel pressure? Inspected hoses swapped the fuel harness to the tank last night. As for my codes code 18,29,41,95 I assume I get when car shuts off. Not sure if I get the 63,41,31 when car dies ALSO LIKE TO ADD. When I was stranded and noticed fuel pressure not rising and the relay DID click! But still not getting pressure to the front as for the fuel pump I’m not sure if it was making noise cuz I was stranded on hiway

Creomod · Apr 15, 2026

Just opened ecu the 3 capicotors still look good not swollen I had them swapped out few years back can a relay maybe ecc relay or fuel relay be intermittent? Sometimes open or sometimes stay shut? I don’t know is it possible? Fuel lines look good no kinks . Vacuum lines do look like they cracked gonna swap them out tomorrow and get connector cleaner spray

Noobz347 · Apr 15, 2026

Wiggle Test!

AeroCoupe · Apr 15, 2026

I mean you have already swapped the relay so the odds are it’s good. Also, I’m pretty sure (@Mustang5L5) that after the ECU commands the fuel pump to prime it then commands the fuel pump to come on only if it receives signal from the PIP.

Creomod · Apr 15, 2026

AeroCoupe said:
I mean you have already swapped the relay so the odds are it’s good. Also, I’m pretty sure (@Mustang5L5) that after the ECU commands the fuel pump to prime it then commands the fuel pump to come on only if it receives signal from the PIP.

The fp relay I did the ecc relay I didn’t just thinking maybe a malfunction in a relay. Usually don’t get trouble with wiring it’s usually a part that goes bad when my car acts up.I swapped the pip,I bought it from O’Reilly I have the dynomid so you can just slip off the gear easily. Maybe wiggle test wires I did look at all grounds. But…… scince I did swap the pip maybe it’s defective? I bought it from orillys but I honestly don’t think it’s the pip . It is easy to swap and mines on warranty

AeroCoupe · Apr 15, 2026

What brand of PIP? Parts stores brands are junk.

Creomod · Apr 15, 2026

AeroCoupe said:
What brand of PIP? Parts stores brands are junk.

Orillys I belive standard brand. I tried to buy one from dynomod I believe. Distbutor out of warranty

Mustang5L5 · Apr 16, 2026

AeroCoupe said:
the ECU commands the fuel pump to prime it then commands the fuel pump to come on only if it receives signal from the PIP.

The ECU does a 2 second prime on key on with PIP signal, jumping the relay commands it on bypassing the ECU. Usually when it's an ECU failure due to hardware (swollen caps) the pump runs continuous. I believe the outside cap (the one near the edge of the board) is responsible for the pump circuit so when it goes the pump runs. There is also a fuel pump transistor that rarely fails.

Don't rule out corrected connections of brittle wiring as well here.

AeroCoupe · Apr 16, 2026

What about after the prime and you are cranking the car? Doesn't the ECU need to see a PIP signal to run the pump?

AeroCoupe · Apr 16, 2026

@Creomod - Do you know if you got the LX-222 or LX-222T? The "T" is their economical line so skip that one if you can. The LX-222 is probably the best one you can get unless you luck across a NOS Ford one.

This seller on ebay has six NOS Ford PIP's. $70 is steep but I would get one if I did not already have one in the box.

Ford Genuine NOS Motorcraft Pick-Up Coil Stator E5PZ-12A112-A, DU-30-A (QTY-1) | eBay

The depth and breadth of parts is massive and spans decades! Condition varies and is described to the best of my ability after a thorough inspection. Boxes are old, musty and dirty.

www.ebay.com

Mustang5L5 · Apr 16, 2026

AeroCoupe said:
What about after the prime and you are cranking the car? Doesn't the ECU need to see a PIP signal to run the pump?

Correct. Although now that I did into this, the initial key on prime might not take into consideration PIP input. Trying to search through 600 pages of A9L strategy but can't find the right ladder logic for key on prime.

But this is crank/run.

AeroCoupe · Apr 16, 2026

I am pretty sure that key on does not require the PIP signal due to the shutter wheel could be in any position and is not moving?

Creomod · Apr 16, 2026

Mustang5L5 said:
The ECU does a 2 second prime on key on with PIP signal, jumping the relay commands it on bypassing the ECU. Usually when it's an ECU failure due to hardware (swollen caps) the pump runs continuous. I believe the outside cap (the one near the edge of the board) is responsible for the pump circuit so when it goes the pump runs. There is also a fuel pump transistor that rarely fails.

Don't rule out corrected connections of brittle wiring as well here.

Gotcha

Engine Fuel not pumping

Creomod

Attachments

AeroCoupe

lube between the nut and the face. I know my lubes

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor

Creomod

Creomod

AeroCoupe

lube between the nut and the face. I know my lubes

Ford Mustang 5.0 A9L A9P C3W A3M X3Z ECU Repair Service

Mustang5L5

That is…until I whipped out my Bissell

Creomod

Creomod

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor

AeroCoupe

lube between the nut and the face. I know my lubes

Creomod

AeroCoupe

lube between the nut and the face. I know my lubes

Creomod

Mustang5L5

That is…until I whipped out my Bissell

AeroCoupe

lube between the nut and the face. I know my lubes

AeroCoupe

lube between the nut and the face. I know my lubes

Ford Genuine NOS Motorcraft Pick-Up Coil Stator E5PZ-12A112-A, DU-30-A (QTY-1) | eBay

Mustang5L5

That is…until I whipped out my Bissell

AeroCoupe

lube between the nut and the face. I know my lubes

Creomod

Similar threads

Engine Fuel not pumping

Attachments

lube between the nut and the face. I know my lubes

Stangnet Facilities Maint Tech... Er... Janitor

lube between the nut and the face. I know my lubes

That is…until I whipped out my Bissell

Stangnet Facilities Maint Tech... Er... Janitor

lube between the nut and the face. I know my lubes

lube between the nut and the face. I know my lubes

That is…until I whipped out my Bissell

lube between the nut and the face. I know my lubes

lube between the nut and the face. I know my lubes

That is…until I whipped out my Bissell

lube between the nut and the face. I know my lubes

Similar threads

Privacy & Transparency

Privacy & Transparency