'87 bad ecm ground?

[hannah2001]

1987 2.9 manual. Got it through a trade, guy claimed it needed a fuel pump... my fault for trusting him. I've read just about every post on this problem and they have helped immensely but now i'm at a loss.

Problem: truck will only crank and run for a couple seconds if you spray ether into throttle body and then it dies. No fuel pump noise when you turn the key and no relays clicking.

what I observed before starting to fix: old fuel pump wires were burnt up, relay bases were burnt up. previous owner had the inertia switch unplugged but had the terminals on the plug jumped with a wire...? previous owner also had 2 different computers in floorboard like they've already replaced the computer

what i have done: brand new EEC & fuel pump relay, used but functioning (both) fuel pumps, fixed burnt wiring going to fuel pump. did not fix relay bases but they (appear to) test and work fine. blue/yellow fusible link connection. Grounding fuel pump relay on OBD1 plug

I read on another post that the blue and yellow wires connected with the fusible links were supposed to be hot all the time, regardless of key position. On one of them, the blue wire was hot and yellow was not so I fixed that problem.

here is where I am lost... I ran a ground from battery to fuel pump relay pin on the obd1 plug. Turn the key and fuel pumps work and relays click like they should. However fuel pumps do not shut off when I do this. The second I remove the ground everything quits working. I get the same result no matter which computer is plugged in. I also have to leave the inertia switch plug jumped. If I plug it in like it's supposed to be nothing works.

My question is would my problem be the ground on the ecm? Inertia switch? Is tracing the ground the only way to fix this? I thought about just running a new ground to that pin but then fuel pump would run all the time...

one of the grounds at the computer has no insulation and just looks fragile... i dont know if the previous owner did this but I attached a photo showing what it looks like. Also, one of the computers that these people left says 3.0L taurus/sable only? Is that an issue?

any advice at all is appreciated !!!!!!

 

[rumblecloud]

Hello hannah2001, Welcome to TRS!

At the risk of stating the obvious, a bad ground can cause all kinds of crap. My 94 had one and I spent a month trying to figure it out.
I don't know about the 87 model years, but when I look to replace my pcm, it is matched to the VIN. Anything else could result in issues.

Good luck with your fix. Others with more knowledge will be along to offer help.

 

[bobbywalter]

follow and ohm the ecm grounds....the two near the battery often become disconnected or broken off.

 

[bobbywalter]

iirc...pin 22 grounds the relay to turn the fuel pump on. make sure that ohms out as well.