I had a random shutdown last night that left me stranded on the side of the road about a mile from home. I got towed home by a neighbor and I've been looking into it this morning. It's the truck in my signature line: 1995 F250, 460, E4OD.

So far, I've ruled out the fuel pump fuse, fuel pump relay (swapped it with the horn relay and it works), and the inertia switch is not tripped.

I went to pull codes and can't get my code reader to work or any codes to flash on the dash using the jumper wire method.

Before I really start digging into wiring between the fuel pump relay and the pumps, could it be that my ECU has died? Would it just die randomly while driving?

 

Well, you're checking the right things. Have you tried spraying starter fluid directly in to the intake to see if she starts? It may well be the ECM as they are getting old and do fail but you could just as easily have an issue in the Distributor and your not getting spark.

 

Either you have lost power or ground to the PCM Compouter or the PCM Computer is bad.
I vote that it is a bad computer.

 

Thanks for the input so far.

I didn't have time to work on it more this afternoon; I'm getting ready for 2 months of week-day travel for work; it's shutdown season in the industrial world in the Midwest, so plants are expecting their instrumentation calibrations to be performed. I've got a full schedule until June, so it'll probably have to sit for a while since my weekends at home will be spent on house projects and general life 'stuff'.

I'm fairly confident it's not spark related. Last time the truck did this to me, the fuel pumps ran but it wouldn't start. I ended up needing to replace both the TFI module and the whole distributor since the PIP sensor was bad as well. I through in a new coil at the same time since that seemed to fix it once before the issue popped up.

Again, I haven't had much time to look around, but I'll take my Haynes manual with me to start looking over wiring diagrams and such. Are there any good ways to test the PCM quickly?

 

What fuel pump fuse are you looking at? Did you look at the large fuses in the fuse box under the hood? I think the third fuse in, in the middle row.

On my '94 I lost the fuel pumps and found the fuse that was blowing and the radio capacitor on the ignition coil was shorting out causing that fuse to blow, causing the fuel pumps to not run. This may not be your problem, but just a thought.

 

Does your check engine light come on when you turn the key on?

 

Yup, I checked the maxi fuse under the hood. It looks and tests good.

 

No check engine light when the key is on, but I also can't get the truck to even start a KOEO test either manually or with a code scanner.

 

No check engine light at all means the computer is either completely fried, or is not getting power (or ground).

I'd start by replacing with the main EFI/PCM relay with a new one, or at least an identical relay in the fusebox.

 

I'll check those out next time I'm home. Thanks for the suggestions.

 

Make sure you check any EFI/PCM related fuses as well.

 

OK, I finally found the time to get the ECU pulled out of the truck. Is there anything I can do to test the function of the ECU on the bench, or is my best bet just to buy a replacement? I'm assuming the relevant part number is

F6TF-12A650-ALA

in my case.

Anything else I need to know to find a suitable replacement?

I did check all of the fuses and relays; I swapped them around with the horn relay/fuse so that I could test each one individually, and they all tested good (horn always worked).

 

Did you check the PCM Computer ground wires?

The PCM Computers ground wires are the two small wires going to the body ground as in the below photo. Also make sure you have the large wire going to the body ground from the NEG post of the battery.


/

 

As a final check, with the key on, Pins 1, 37 and 57 on the PCM connector should have +12v on them.

 

All of the grounds appear to be in good condition. I'll grab my DMM and check resistance between all of them as a final check.


I'll check those too.
Pin 1 is (B+) Keep Alive Power Input
Pin 37 is Ignition (Hot in start or run)
Pin 57 is Ignition (Hot in start or run)

It looks like pin 22 is the "Fuel Pump Enable" which I'm assuming is the ground to complete the circuit for the fuel pumps. If I ground that, at the pumps start, that should indicate that my problem is in the ECU correct?

It also looks like I should check between ground and pin 16 for Ignition ground (not likely since I see spark), 40 for Ground, and 60 for Ground.

Edit:

It appears that my grounds are good.

Power only appeared on Pin 1 though. I couldn't get a reading on pins 37 or 57 though. Does anybody have a diagram of those circuits? I'm trying to find my Haynes manual, but I'm not finding it at the moment (moved too many times since I last used it).