Fuel 93 5.0 fuel problem

bjohnson6519 · Apr 27, 2025

Hello I have a 93 5.0 with GT 40 heads swapped in to a 65. Recent problem I have now is too much fuel. If I start it up runs rough and black smoke. Pulled plugs smell like gas. But If it pull the fuel pump relay it starts an runs great until it runs out of fuel. Any suggestions what is causing to get too much fuel? Thanks Brian

AeroCoupe · Apr 27, 2025

Have you checked for any codes? If not and if you do not know how then go here:

Electrical Thread 'How To Pull Codes From EEC-IV In 86- 95 5.0 Mustangs'

Jan 27, 2016

@Noobz347 - The code dump procedure isn't in the sticky - you may want to add it...

Dump the codes: Codes may be present even if the Check Engine Light (CEL) isn't on.

Dumping the computer diagnostic codes on 86-95 Mustangs

Revised 26-July-2011. Added need to make sure the clutch is pressed when dumping codes.

Codes may be present even if the check engine light hasn’t come on, so be sure to check for them.

Here's the way to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for...

Have you checked the fuel pressure? Have you checked for fuel in the vacuum line that connects to the fuel pressure regulator? If there is fuel then it’s a sure sign the regulator is bad.

Could be the return line is pinched or kinked.

bjohnson6519 · Apr 27, 2025

Replaced the regulator and fuel pressure holds at 29.

AeroCoupe · Apr 27, 2025

Fuel pressure should be 39 psi with the vacuum unhooked from the regulator and the vacuum line plugged.

bjohnson6519 · Apr 27, 2025

Yes that is what I got. All spark plugs are black and smells like gas.

Mcmahst · Apr 27, 2025

What is the vacuum reading at idle and at what idle speed? Is the engine hunting for a steady idle?

AeroCoupe · Apr 27, 2025

Before we go down any more rabbit holes did you check for codes?

bjohnson6519 · Apr 27, 2025

Code 23, 67, 81,82, 85
On a Foxbody Mustang 5.0, code 23 indicates a problem with the Throttle Position Sensor (TPS

Others are Emission codes
TPS wouldn't cause my problem would it? Again with fuel pump replay pulled car runs good until all the fuel in the rails is gone. With fuel pump running sputtering a lot of black smoke.

AeroCoupe · Apr 28, 2025

Well let’s see here…Code 23...yes it would cause problems. ECU looks at the TPS position so if it’s providing bad info to the ECU then the ECU will output bad info. Need to fix this.

Code 67 will not let you run KOER diagnostics so you may be missing codes related to that test. See this thread:

Thread 'Code 67'

Dec 29, 2017

1988 Mustang factory V8, 5 speed car. Mass Air conversion done with A9L computer. When KOEO is done I get code 67 along with some EGR codes too. Trying to fix the 67 code. When codes were pulled a/c was off, car in neutral and clutch pushed in. A Tr 3550 tranny is in the car and the sensor is plugged into the tail and connected. Have also tried unplugging the switch on the clutch pedal and jumping the connector and still get the code. The car has a build date of 10/87 and has the speed density O2 harness (5 wire harness, no loop). Any help is appreciated! Thanks

So see about fixing those two codes, clear the codes, get the motor up to operating temperature and then dump the codes both KOEO and KOER.

bjohnson6519 · Apr 28, 2025

I am pretty sure it has something to do with the ECU everything else is new. I had a chip in it I was messing with it now it is dumping fuel in cylinders.

Mcmahst · Apr 28, 2025

That ^^^^^ would have been good to lead your first post with.

bjohnson6519 · Apr 28, 2025

Yeah sorry my bad. I assume there is a compacitor that controls the fuel injectors opening. The tune I bought was tweecer. Anyone know anyone the rebuilds the old A9P ECM ?

91AOD5.0LX · Apr 28, 2025

Home - ECU Exchange

ECU Exchange specializes in the re-manufacturing and repair of engine control modules.

www.theecuexchange.com

They refurbished my A9P in 2022 and it’s worked perfect ever since.

AeroCoupe · Apr 28, 2025

So you had a Tweecer on it and evidently the car was tuned and ran well. You pull the tweecer off and now it doesn't run well. Can you pop the tweecer back on and see if it runs right or did you change things since it was removed? Does it now have the stock MAF and injectors or a calibrated MAF and larger injectors? Basically is there anything in the motor that is not stock other than the GT40 heads?

bjohnson6519 · Apr 28, 2025

Car started running bad with the Tweecar still installed it ran decent then it didn't. Where to begin it's a 93 Cobra S VT block and GT40 heads fresh rebuilt with mild cam. Intake is off an Explore larger throttle body new mass air, JBA headers, painless wiring harness, A9P ECM, Tanks intake fuel pump, Tweecar tune but could never get that to run right or hook up. All in a 65 coupe. A smarter guy would have just put a carb on it and drove but after investing years and money here I am and here it sits. It ran decent before just idle issues now black smoke. Thanks for the help.

gkomo · Apr 28, 2025

Sensor gone bad? Like an O2 sensor or something?

bjohnson6519 · Apr 28, 2025

It never ran great but good now horrible with the Tweecar or Without. Only thing that makes it run great is priming the pump then pulling the relay. Car runs smooth until fuel runs out. Only thing I can figure is the ECM is firing all the injectors at once dumping fuel in every cylinder at once.

Noobz347 · Apr 28, 2025

What color fuel injectors are installed in the car?

Better yet: Post pics of the Fuel injectors, Mass Air Meter, and TwEECer unit. Post up an image of your ECU too.

bjohnson6519 · Apr 28, 2025

Orange injectors

Noobz347 · Apr 28, 2025

Swap the TPS, clear the KAM and let us know what happens.

Fuel 93 5.0 fuel problem

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

Electrical Thread 'How To Pull Codes From EEC-IV In 86- 95 5.0 Mustangs'

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

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

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

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I have a slight sag in my rear

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

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now i can hopefully expect to receive the shaft

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