Stalls, Have to Sit with Battery Disconnected, Then Starts/Runs Fine

[DannyB1122]

So I've been having an intermittent issue for the better part of the last 2 years on my 87 GT, and I've been stuck scratching my head. Periodically, the car will stall and will not re-start unless I disconnect the negative battery terminal and let the car sit for a few minutes. When it stalls and I try to re-start it, the engine turns over but doesn't fire up. If I try to re-start it too quickly, it seems to vapor lock, resulting in my having to have it sit for longer. It doesn't happen all the time, but it's just enough to be a pain in my ass, as it happens at the most inconvenient of times, and almost never in my driveway or garage. I've replaced the fuel filter, thinking that was the culprit. I've replaced the fuel pump, thinking that was the culprit. Neither have solved the problem. About 7 or 8 months before this issue came about, I replaced the ignition module by the distributor with a supposed genuine Motorcraft part (I say "supposed" because I've heard that it's basically Chinesium with a Motorcraft logo on it). Could that be the cause?

 

[General karthief]

Yes.......

 

[DannyB1122]

I’ll try that. I’ve also heard that it could be the ECM or the starter solenoid fusible links. Not sure it’s the ECM in this case since I have an extra and it’s done this with each one installed.

 

[Noobz347]

Has there been any work done to the valvetrain?

Have you pulled codes, just to check?

 

[General karthief]

Let me expand, now you're gonna waste money randomly changing parts and not knowing if it's fixed until you're 'awe sht' alongside the road again.
I mean you could get lucky but then
Here's what I'd do: carry a spark plug tester, 12 volt test light or DVOM and a can of starting fluid, when it dies, give it a shot of the 'flamethrower in a can', if it starts up then dies=fuel related, no start= electronic thing, now you have a direction to go in.
I will admit given the symptoms you describe I'd just throw some 'happy cash' at a new distributor.
There ain't no app for that but there is a tech thread:

Cranks OK, but No Start Checklist for Fuel Injected Mustangs

Cranks OK, but No Start Checklist for Fuel Injected 5.0 Mustangs model years 1986-1995 A word about this checklist before you start: it is arranged in a specific order to put the most likely failure items first. That will save you time, energy and money. Start at the top of the list and work...

www.stangnet.com

 

[DannyB1122]

Has there been any work done to the valvetrain?

Have you pulled codes, just to check?

No work to the valve train, everything is stock. Only code I get is 33, which is the EGR valve.

 

[DannyB1122]

Let me expand, now you're gonna waste money randomly changing parts and not knowing if it's fixed until you're 'awe sht' alongside the road again.
I mean you could get lucky but then
Here's what I'd do: carry a spark plug tester, 12 volt test light or DVOM and a can of starting fluid, when it dies, give it a shot of the 'flamethrower in a can', if it starts up then dies=fuel related, no start= electronic thing, now you have a direction to go in.
I will admit given the symptoms you describe I'd just throw some 'happy cash' at a new distributor.
There ain't no app for that but there is a tech thread:

Cranks OK, but No Start Checklist for Fuel Injected Mustangs

Cranks OK, but No Start Checklist for Fuel Injected 5.0 Mustangs model years 1986-1995 A word about this checklist before you start: it is arranged in a specific order to put the most likely failure items first. That will save you time, energy and money. Start at the top of the list and work...

www.stangnet.com

When it happened last night, after having it sit for a bit I tried to start it, it kicked over and then died. Then I let it sit some more and after a while it started. What makes this even more complicated is that it’s totally random. It doesn’t do it every time I drive the car. It doesn’t even do it every other time or every third time. It’s almost like it’s possessed lol

 

[AeroCoupe]

ECU could be bad but you need to go through the check list that the General linked before you do anything else.

Ford Mustang 5.0 A9L A9P C3W A3M X3Z ECU Repair Service

Ford Mustang 5.0 A9L A9P C3W A3M X3Z ECU Engine Computer Repair ServicePlease fill out the R&R form here once you've placed your order.Easy repair process1. Purchase repair service (this way helps us keep track of what's coming in for repair)2. Include order number with your computer and mail to...

www.theecuexchange.com

 

[General karthief]

I mean I could tell you to replace this dohicky or that one but what do you do when it randomly stops again? It could be a loose connector or a frayed wire, think of it this way, it's a glob of electricity dancing around under the hood, it carries information, the flow is being interrupted, jumbled, like a computer screen jumping, you have to find the interruption, go through the checklist I linked and you'll find it, intermittent interruptions are hell to find, usually easily fixed.

 

[Noobz347]

I think you're down to:

PiP
TFI
EEC
Possible fuel pump (with no lean codes, I find this unlikely)

 

[91GTstroked]

I personally would pull the ECU out and take the cover off if it and look at the capacitors. They have also caused problems with the function of the fuel pump.

I mean that ECU if original isn't far from 40 years old!

If you want it checked out and fixed it needed contact ECU Exchange.

 

[DannyB1122]

I replaced the TFI earlier today, and the fuel pump is new as of last summer, so if it does it again, I think I’m going to put in a new EEC relay followed by a new distributor.