88 Mustang dies, won't restart until a key cycle

[toeffer]

Hello,

I am chasing a problem that continues to get the best of me. The car runs great, but just dies. No power is lost inside, everything still works as it should. If I try to crank it without cycling the key it will crank forever and not start. As soon as I cycle the key it starts right back up.

When this happens I have had a fuel gauge on it, and it is not losing pressure.

I have replaced the TFI, PIP, COIL, IGNITION SWITCH, ECU.

Any thoughts would be appreciated.

 

[General karthief]

Do you hear the fuel pump running when it shut off?

 

[toeffer]

Its hard to tell the timing, but when the car shuts off I believe the pump does too. I do know that its not losing pressure until well after it dies. As soon as I cycle the key I can hear the pump re prime.

 

[AeroCoupe]

Possibly the fuel pump relay failing or it could be the ECU. ECU Exchange is where most folks are sending them. They are getting up there in age (37 to 30 years old) and what most find is the capacitors are failing as they age out.

 

[toeffer]

Possibly the fuel pump relay failing or it could be the ECU. ECU Exchange is where most folks are sending them. They are getting up there in age (37 to 30 years old) and what most find is the capacitors are failing as they age out.

I had the problem with the stock ECU, it has since been switched over to a MSPNP2 and is having the same issue. Would the fuel pump relay failing cause the car to shut off even though it still has pressure when the car dies?

 

[AeroCoupe]

Does the MSPNP2 look for a fuel pump run signal and if so when it does not see a run signal will it shut things down? Does the car stumble or just die?

If the fuel pressure is not dropping when it dies then I am doubting its fuel system related from the tank to the fuel rails. You are either loosing spark signal, injector pulse signal, or both. Check your ECU harness grounds and just for grins check the ECU relay which I believe is mounted above the stock ECU location.

 

[toeffer]

The MSPNP2 supplies a ground to FP relay to engage the pump. I don't believe it has any feedback for when the pump is running.

It does not stumble at all it just dies. ECU grounds at the battery from what I understand of the diagram, there is a second ground down by the ecu but it is for the sensor grounds?

I am going to try and swap out the ECU relay, but I have not yet.

 

[AeroCoupe]

I saw your post over in the digital self-tuning forum and my bet is they will find it.

 

[rednotch]

Next time it happens, don't cycle the key, and start checking power to everything that should have key on power, check spark etc. I have had new ford ignition switches fall apart in days, long after the recall, even when dealer installed on a open recall. Theres still bad old stock floating around. But I would guess its wiring issue over a bad part if cycling the key temporarily fixes it.

 

[toeffer]

I saw your post over in the digital self-tuning forum and my bet is they will find it.

I hope so, my tuner says there’s nothing in the tune or logs that shows anything abnormal

 

[Shuttleman83]

Check your charcoal canister, vac lines to it, or sensors.

 

[General karthief]

I'll go out in left field here and ask you to start the car and then wiggle the key switch, wiggle while turning the switch back and forward.
Does it die or stumble?

 

[90sickfox]

Sounds like a bad wire in the ignition switch connector. Might help to unplug it and tighten all the connections a little with a pic or small screw driver. Did any of the wires look burned or heated up when you replaced the switch.

 

[toeffer]

Check your charcoal canister, vac lines to it, or sensors.

It no longer has a canister, but I’m intrigued to hear where you’re going with this?

 

[toeffer]

Sounds like a bad wire in the ignition switch connector. Might help to unplug it and tighten all the connections a little with a pic or small screw driver. Did any of the wires look burned or heated up when you replaced the switch.

Everything looked great on the wires. No burns all the clips were in good shape, they all locked into place and gave them a quick tug to make sure they were seated.

 

[AeroCoupe]

You need to link this thread and the one over in the Digital Self-Tuning forum so folks are not chasing their tails here.

 

[General karthief]

Why is your charcoal canister not installed/functioning?
I think you need to probe the ignition 'on' wires at the time the engine shuts down, did you do the 'key wiggle' test?

 

[Shuttleman83]

It no longer has a canister, but I’m intrigued to hear where you’re going with this?

Went through a similiar issue, was usually after putting gas in. Was the canister and the vac lines going to it and in my case, the PCM.

 

[AeroCoupe]

@Shuttleman83, can you expand on what the causes of the car dying were and how they were solved as that may help the OP.

 

[Shuttleman83]

Well my particular car was a bit newer but it basically was the same thing. It would run great, die out, then need cycled to eventually restart. It was the charcoal canister and or evap lines on my particular car.