What schematics are you working from now? Does it mention what the ground number is (Gxxx)? And you do not have to have a tech 2 tool to follow through the book diagnostic procedure. It does make things easier.

 

One is in this thread up a few, the other is "95_fuel_pump_SC.jpg" from another thread, but I have looked at so many threads I don't know where I found it.

They both refer to "see ground distribution schematics" or something to that effect. I wondered if that was a specifiic file or files.

Bruce

No tech tool, I have a V.O.M. If a major computer is needed I will make a roadworthy jumper to bypass the relay and drive it to a competent shop for analysis.

 

You mean this picture:


The reference to the ground distribution schematics is just to see what else is grounded at that location. The ground for the fuel pump relay is shared with quite a few other things. It is ground number G102. The fuel pump and sender use ground G427.

IIRC, G102 is located on the back of the passenger side cylinder head. G427 is located on the frame back near the tank.

 

What is your instinct on:

Should I "create" a new ground path for the fuel pump relay coil to, e.g., the firewall ground strap?

I had hesitated because I was assuming there might be other electronic 'logic' decisions being made to that coil circuit, though to me they should be made by the VCM on the feed side of the relay.

My head hurts from all this.

Bruce

 

You could ground it to a different location. A ground is a ground.

 

I will have to accept a lot of blame here and now. It was my own carelessness that prevented the relay from operating properly!!!

I had pushed a test probe or two for voltage or continuity, too often, with too much force, into the socket terminals for the relay. I thought I was just getting past the plastic. I was spreading the terminals to the point of not being able to function properly when I put the relay back in place.

I discovered this when I ran a supplemental ground, by putting a bit of wire in with the ground leg of the coil. The engine immediately started and ran normally. I then pulled the ground line from the braided strap on the firewall. It did not shut down. It also started normally. I have now cut the wire I added as aux/ground at the edge of the fuse/relay block, leaving the bit that restored the contact for the relay.

Lesson learned, and maybe one of you will use a proper relay pin instead of a round probe to test and jump circuits while you trouble-shoot.

I seem to be back in operation, but I may look for a new relay/fuse block to be sure for the future. It only takes a few minutes to replace, if you get everything back in its proper place!

Bruce

This forum is a vuluable resource. The problems we face, (and in my case, sometimes cause), are dealt with by guys like Kyle, with remarkable patience and care. Thank you, one and all.

 

Wow. Who would have thought of that...? Glad you found it!