Popps then Shuts Off again.

AeroCoupe · Jul 17, 2025

Code 18 here:

Thread 'Help Code 18'

Feb 18, 2017

I have a 1989 Mustang GT 5.0 5 speed the month I have a 80 millimeter mass air meter calibrated for 24 injectors 65 throttle body Holley intake manifold upper and lower ported stock heads 1.7 rocker arms 24 injectors BBK shorty headers Dynomax super turbo mufflers with pipes stock H pipe with for cats timing is set ten stock it runs for like 10 to 20 seconds then it just turns off no warning but when I put back the old rotor it's good again and it doesn't turn off but when I put a brand new rotor (Motorcraft) I get code 18 and it runs very rough smells rich help

robw13 · Jul 24, 2025

Now it won't idle for crap, keeps stumbling up and down then dies. New iac, dizzy and temp sensors. No codes. Maybe fuel issue? What fuel pressure is it supposed to be at?

AeroCoupe · Jul 24, 2025

39 psi with the vacuum disconnected from the FPR. Plug the vacuum line. Also, if the vacuum line has gas in it the FPR is fubar.

General karthief · Jul 24, 2025

32 psi (+-) engine idle, vacuum hooked up to FPR, 40 ish psi vacuum line off FPR.
Oh, and there is always a code, if the computer does not talk to the scanner/reader then it needs checked out. Most should be checked out at this age anyway. Remember, manufacturers don't design/build stuff to last much more than 20 or so years, they don't care after that.

AeroCoupe · Jul 24, 2025

If all checks out you will get a code 11 every time. This both one KOEO and KOER. If you do not get this the General said above the ECU is most likely fubar from age and need to go to the ECU Exchange for a repair.

Ford Mustang 5.0 A9L A9P C3W A3M X3Z ECU Repair Service

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www.theecuexchange.com

robw13 · Jul 24, 2025

So far it's talking I think, shows code 11,10,11 only 18 if the dizzy plug is taken out. Is there a way to check the ecu without opening it up?

nickyb · Jul 24, 2025

My money is on the new distributor, I went threw three part store ones that we're all crap.

Noobz347 · Jul 24, 2025

Check the vacuum hose going to the FPR (even if you've already checked the FPR).

Check your return line and make sure it's not pinched or blocked. I would even rig up a temp return line running into a gas can to check this out.

robw13 · Jul 25, 2025

Frp line is dry when primed or running. Hooked fuel pressure gauge up, no psi on prime or running. There's fuel at the schrader valve. Codes 18 and 96 now. 18 is cause of messing with dizzy.

AeroCoupe · Jul 25, 2025

Where did you hook up the fuel pressure gauge? If you did it at the Schrader valve I’m pretty sure you have to remove the stem to get one to work.

robw13 · Jul 25, 2025

Actually did not that, the fitting screwed on just fine though. Is the stem on the valve or the guage?

AeroCoupe · Jul 25, 2025

It’s the stem in the schrader valve. I don’t think most pressure gauges depress it when you install them so you will never see a pressure reading. Think of them like the valve on a wheel to inflate a tire.

robw13 · Jul 25, 2025

Do I remove it or the valve then install the guage?

Noobz347 · Jul 25, 2025

robw13 said:
Do I remove it or the valve then install the guage?

Remove the [valve stem core] from the valve on the fuel rail and then connect the fuel pressure gauge.

The tool used to remove the [valve stem core] is the same as the one that you use on valve stems on wheels and tires.

Any of those tools will work. So will a tiny flat-tip screw driver (in a pinch), if you're careful and don't booger up the threads.

robw13 · Jul 25, 2025

I removed it but the fuel pressure kit doesn't have 1 that fits the slot. Rented a fuel pressure kit from oreillys

AeroCoupe · Jul 26, 2025

I'm not sure that kit will work but it might. I would suggest you just get a permanent pressure gauge if you are not using the schrader valve for anything else. Not cheap but its what I ran for years before going to an Autometer full sweep electric one. This particular kit does not require the removal of the internal valve which is a plus. I removed it when I installed the Autometer gauge as it is in the bag with the Kirban manual gauge.

1984 1985 1986 1987 Buick Regal Grand National Turbo T T-Type GNX EFI FUEL PRESSURE MECHANICAL GAUGE KIT #6629

www.kirbanperformance.com

I still have the instructions and scanned them:

Noobz347 · Jul 26, 2025

robw13 said:
I removed it but the fuel pressure kit doesn't have 1 that fits the slot. Rented a fuel pressure kit from oreillys

Removed what? The stem core?

Just set it aside. Nothing goes back into the fitting until you're done.

With the valve stem core removed, attach the fuel pressure gauge and run your checks.

When you're done, re-install the valve stem core and check it for leaks.

robw13 · Jul 28, 2025

Also, what brand of fuel pump relay is good to use other than OEM?

AeroCoupe · Jul 28, 2025

Bosch 30A relay.

https://www.waytekwire.com/product/Bosch-0332019150441-Mini-Relay-SPST-30A-12VDC?utm_source=google&utm_medium=cpc&utm_campaign=17557836368&gad_source=1&gad_campaignid=17335616382&gclid=EAIaIQobChMI5v7-9JfgjgMVfjjUAR26NAE9EAQYASABEgIT6vD_BwE

You can find them everywhere so just do a search. I use them for the fuel pump relay and WOT relay on my 93.

robw13 · Jul 31, 2025

Did more testing/digging. Check codes KOEO got 10 11 18. KOER, got thru cylinder 8 before dieing, codes 21, 44, 94.
Found a big hole in the main rubber 3/4" hose to air pump. Guess thats the 44/94, but what about 21? What would be causing 18 again?

Popps then Shuts Off again.

AeroCoupe

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

Thread 'Help Code 18'

robw13

AeroCoupe

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

General karthief

wonder how much it would cost to ship you a pair

AeroCoupe

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

Ford Mustang 5.0 A9L A9P C3W A3M X3Z ECU Repair Service

robw13

nickyb

I gotta say i never painted my nuts, Never Ever

Noobz347

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

robw13

AeroCoupe

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

robw13

AeroCoupe

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

robw13

Noobz347

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

robw13

AeroCoupe

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

1984 1985 1986 1987 Buick Regal Grand National Turbo T T-Type GNX EFI FUEL PRESSURE MECHANICAL GAUGE KIT #6629

Noobz347

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

robw13

AeroCoupe

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

robw13

Similar threads

Popps then Shuts Off again.

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

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

wonder how much it would cost to ship you a pair

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

I gotta say i never painted my nuts, Never Ever

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

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

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

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