southernyankey1

Had to get my old girl towed home again tonight! By a Dodge Ram owned by a really good friend...lol. she just stopped running at 70 mph on 95 south tonight...Awesome! No fuel pressure no spark no codes no bypass to run the fuel pump! Hopefully the ECM shop i got it from a month ago will swap it out tomorrow! i checked and rechecked every possible ground i could find in the engine harness a month ago when i changed the last one out, maybe i missed something or it was just a weak unit... I have the little POS Actron code reader(whiich is just a $30 paperclip) and it made no difference in my ability to pull codes.

such is life when you own a 22 year old truck I guess.

LobstahClaw

Ohh man ... that sucks.

I dunno ... i read somewhere that the original ECM was intended to last the life of the truck. What that means is anybody's guess. Did they intent a service life of 20 years or was it supposed to last indefinately ?

You might want to look into what caused the original to fail.

Felicia was saying the other day that Ford had a service bulletin out on the O2 sensors causing the ECM's to fail.

One part goes bad and it starts a domino effect that takes out some others.

You might want to look into that to see if it pertains to your truck.

Point being: You could replace the ECM again but if there's an underlying cause of the failure then the repair won't hold.

southernyankey1

it's something else. I took it back to where i got it and he pulled it apart and all the capacitors are still good and nothing was burnt on the board. My fuel gauge stopped reading about an hour before she went down and i have to pull the tank tomorrow to see what's up with that.(OF COURSE, i just filled it up yesterday morning!..lmao!!!) It still wont give me any codes or go into diagnostic mode for that matter. I dropped the steering column and swapped the ignition switch with a known good unit and no change so i'm looking at tracing power to the ecm tomorrow. Luckily i have a spare fomoco fuel pump in case that was the real issue...

Trouble shooting these old trucks is a real PITA sometimes. At least I can work on it without fear of killing the useless Ford warranty...lol. I'm sure it will turn out to be something stupid and off-the-wall, just like it always is on the old girl.

LobstahClaw

I know what you mean. It can be uncommonly difficult to track the source of the problems sometimes but you earn a good education in the process.

That's a useful skillset to have. It's nice to be able to do for yourself and not depend on someone else.

You might not know about a GM or a Dodge but if you learn the truck you drive inside & out you've really got something.

southernyankey1

ok
swapped the ecm again with the new pump assembly. No change. My fuel guage pegs out past full unless i pull the fuse for the guages...very strange. The ECM will not go into diag mode and the pump will not run! Is there a fusible link somewhere i'm missing? i can't see any blown fuses and i can't get it anywhere to get it looked at....The ecm and the fuel pump relays are new fomoco's and have been double checked.

does anyone have a FORD factory manual on pdf? I have the Haynes one and it is pretty much useless for diagnosing this stuff...

LobstahClaw

Okay ... you ruled out your EEC.

You have three problems.

1: The fuel guage pegs out.

2: The fuel pump will not run.

3: Your code reader isn't working for some reason ?

It could be that they're three seperate problems with seperate causes. It may be that they root from the same source.

Take the most important thing first.

Do you have power to your fuel pump ?

I just retired a 1990 E-150 with a 300 I6 from service a few months ago. Last winter there was a problem with the motor just dying as it was going down the road. Finally it came to a point where the van would just crank and not start.

It took about a week to find the problem.

If i remember right there was a low pressure fuel pump in the tank. Two thirds the way forward a high pressure pump was mounted inside the frame rail.

There was no power going to the high pressure pump.

I thought it might be the fusible link. The owner's manual told me where to find it. It was in the wiring harness on the upper right hand side near the firewall. Got power on both sides of it so the link showed all good as far as there.

Looong story short it turned out to be a failure in the wire that sends power from the engine compartment down underneath to the pump.

Most people start troubleshooting from the engine area & work back. For me ... it just led to confusion and a week's worth of wasted time.

It might be more fruitful to start at the back and chase that color coded wire forward ... checking for power as you go.

southernyankey1

Thanks...it's starting to get frustrating. LOL

Ran a jumper instead of the code reader, same thing. No diag output. checked at the tank...no voltage. Have voltage on both sides of the fuel relay so it's prob a short in between but it doesn't explain the fuel level gauge pegging out unless the harness is grounded out, but then that would blow the relay most likely. We shall see i guess

jumper from test harness connector to ground does not run pump. error code 52 , 212,152 which make no sense unless i'm looking at wrong list...

southernyankey1

ran a hot wire to pump and it runs but like ****.can't get it to 55 mph..i give up.
now trans is stuck in reverse...lmao. cant get it out of gear. I officially hate this obd1 pos engine management system. If it was a 302 i'd rip it all out and run a carb and a manual pump and get on with my life...i'm gonna tow it to a mechanic tomorrow and pray he doesn't screw me too badly. I know it's something stupid but i'm out of ideas the fuel guage is pegged out and i get 6 volts through the pump harness...WTF?" There's nothing left to replace at this point and i didn't add anything to the truck to cause a short