Electrical 93 5.0 No Injector Pulse

machinermac · Jul 26, 2026

Just picked up a 93 5.0 because the seller was not a car guy and just wanted to drive it. I have run down as far as I understand the fuel system pulled the intake and checked fro 12v at each injector all good did continuity test from each injector ground back to the ecu plug all test good. None of the injector wires will flash a noid light. If I have the intake on and shoot starting fluid at it it does run (not perfectly) so I do have spark and timing seems right.

The next previous owner did some mods like a cam and suspension/frame stabilizers but the ECU and fuel look mostly stock. Looking for some direction on where to look to next before I start talking about a new ECU or just installing a standalone.

Noobz347 · Jul 26, 2026

Pull codes:

OBD1 readers are cheap on Amazon or you could pull codes with a paperclip if you are so inclined.

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...

machinermac · Jul 26, 2026

Noobz347 said:
Pull codes:

OBD1 readers are cheap on Amazon or you could pull codes with a paperclip if you are so inclined.

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...

jrichker

Replies: 10

Forum: Fox 5.0 Mustang Tech

As of yet I cannot find a STI or loose cable that should be in that connector anywhere near the self test connector. There is a similar connector near the starter solenoid but its just black wires. I do have a reader but I dont want to fry a possibly good ecu connecting the wrong thing.

AeroCoupe · Jul 26, 2026

My guess is the PIP but need to pull codes first.

machinermac · Jul 26, 2026

Was able to trace the line back from the ECU plug it got moved into the STO but when jumpered I get no codes not even 11. Got to do some more testing but if I can't get codes out of it the former owner was screwing with the ECU and it might be shot.

JD1964 · Jul 27, 2026

Can you hear the fuel pump prime when you turn the key to the run position? The pump should run for a couple seconds and then automatically stop.

Mustang5L5 · Jul 27, 2026

TPS issues can also cause this. Essentially if the TPS returns full 5V sensor ref the ECU will not fire the injectors.

But, sounds like you might have some ECU issues. I second the "do you hear the pump prime" when you cycle the key question

machinermac · Jul 27, 2026

Pump runs continuously in koeo.

JD1964 said:
Can you hear the fuel pump prime when you turn the key to the run position? The pump should run for a couple seconds and then automatically stop.

DadLife0724 · Jul 27, 2026

machinermac said:
Pump runs continuously in koeo.

Shouldn't run continuously. I'd pull the ecu and crack it open and inspect it. Look for anything out of the ordinary. Corrosion, swollen and/or loose capacitors. I am by no means an expert at these ECU's but when I opened mine up I found the issue pretty quickly.

JD1964 · Jul 27, 2026

If you do need an ECU, don’t risk buying a used one. Send yours in to the repair service for exchange

Mustang5L5 · Jul 27, 2026

Continuous pump good sign the ECu need a rebuild. You can likely open it up and take a peek at the capacitors, or test the pin 46 trace

JD1964 · Jul 27, 2026

Also, considering this car is new to you, you need to make sure which ECU service tag belongs in the car because they are not all configured the same. This includes the possibility that someone re-pinned the harness for a transmission swap. If that was done and the wrong ECU was used, it might explain a failed ECU. You want to avoid installing a replacement and having it fry the moment you turn the key on. The most common service tags are A9L and A9P. I’m not sure which one it is but one is interchangeable with harness modification and the other is not. I think the A9L is the interchangeable one but don’t quote me on that. If I’m wrong then someone please correct me.

JD1964 · Jul 27, 2026

Here’s the ECU exchange service that some of on here have previously used. I’ve heard no complaints about then thus far

https://ebay.io/m/9o6AEY

AeroCoupe · Jul 27, 2026

Direct link to their website is here:

1986-2004 Ford Mustang A9L A9P ECU Repair Service

1986-2004 Ford Mustang A9L A9P ECU Repair Service Engine Computer Repair Please fill out the R&R form here once you've placed your order.ORInclude a note in the box with your order number and vehicle symptoms.A Trusted Product with LIFETIME WARRANTY QUICK TURN AROUND TIMEDomestic and...

www.theecuexchange.com

Lots of us here have used them and they do a good job.

gkomo · Jul 28, 2026

+1 on ECU Exchange. I sent them my ECU for no reason, just as an 'insurance policy' to make sure it was fine. Car ran, no reason to, they still found a bunch of stuff wrong and fixed it. Now i know my A9L is good for many years to come.

Willybill32 · Aug 1, 2026

gkomo said:
+1 on ECU Exchange. I sent them my ECU for no reason, just as an 'insurance policy' to make sure it was fine. Car ran, no reason to, they still found a bunch of stuff wrong and fixed it. Now i know my A9L is good for many years to come.

I second that. I had a tune on my ‘86 and still wasn’t real satisfied. Sent the ECU to ECUExchange and they found and fixed several issues.

Bill

Electrical 93 5.0 No Injector Pulse

machinermac

New Member

Noobz347

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

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

machinermac

New Member

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

AeroCoupe

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

machinermac

New Member

JD1964

there is enough sticking out to grab on to

Mustang5L5

That is…until I whipped out my Bissell

machinermac

New Member

DadLife0724

Active Member

JD1964

there is enough sticking out to grab on to

Mustang5L5

That is…until I whipped out my Bissell

JD1964

there is enough sticking out to grab on to

JD1964

there is enough sticking out to grab on to

AeroCoupe

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

1986-2004 Ford Mustang A9L A9P ECU Repair Service

gkomo

now i can hopefully expect to receive the shaft

Willybill32

But at least it's tight!

Similar threads

Electrical 93 5.0 No Injector Pulse

New Member

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

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

New Member

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

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

New Member

there is enough sticking out to grab on to

That is…until I whipped out my Bissell

New Member

Active Member

there is enough sticking out to grab on to

That is…until I whipped out my Bissell

there is enough sticking out to grab on to

there is enough sticking out to grab on to

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

now i can hopefully expect to receive the shaft

But at least it's tight!

Similar threads

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