Weird ground, fixed

[Don W.]

I discovered recently that my truck doesn't do the "run the fuel pump for 2 seconds" thing every time. It's random. Naturally it's hard to start occasionally.

Anyway, I'm dutifully following the flow chart in the manual. I'm to the point where I'm checking the ground circuit from the ECM that ties into the o2 sensor ground and ends up at the rear of the block drivers side. That's where I stopped. Haven't removed the coil to gain access yet.

What's weird is I loose ground continuity almost everywhere with the bat sw off. (I haven't checked every single one.) That doesn't make any sense. I only switch the + side. Everything that has a ground should still have a ground continuity checker wise. IE a test light won't light unless it's bat powered but a meter should show continuity. Or to say it another way if I switch off the + side I should (and do) loose all circuits that would be hot. But ground doesn't go away. All the grounds should show continuity to each other, even if the bat was removed. (Minor exception is the inj grounds but that's not the issue. Truck runs fine once started.)

Anyway, I'm gonna jump on this first thing tomorrow. Maybe a fresh brain will help. :roll: Meantime comments appreciated.

Maybe it's me. Assuming I actually find something I'll let you know.

Thanks

 

[blue83z]

Re: Weird groun, maybe

Re: Weird groun, maybe

Sy or Ty?
Sy has a ground strap at the filler door. That was the problem on 2649 when I dug it out of the crap.

 

[Don W.]

Re: Weird groun, maybe

Re: Weird groun, maybe

Sy or Ty?
Sy has a ground strap at the filler door. That was the problem on 2649 when I dug it out of the crap.

Syclone. The filler door? You mean fuel? Anyway, the bat is in the bed and grounded to the frame. Hot lead goes from bat to switch located to the left of the license plate using the space once occupied by the light. No cutting of cladding involved. From there it goes up the pas side frame rail to the starter. A 10g wire goes from there to the alt like stock and the truck is fed from there. Except when the alt failed reciently there has never been an issue on the pos side of this setup.

When R&Ring the motor I try to be very careful with all the various grounds but maybe something broke. The ground in the circuit in question is the one at the rear of the motor, drivers side. I don't bolt it to the back of the head (stock) but to the last manifold bolt that side. To inspect I'll have to remove the coil/MAP. First on the list in the AM.

Like I said this may be an issue or maybe it's me. I'll know more tomorrow.

Thanks.

 

[Don W.]

Re: Weird ground, maybe

Re: Weird ground, maybe

Well I guess it was me. Every wire that I know of on that truck that is black is a ground wire. I've got this black wire at the ECM that's not grounded. Hence the wild goose chase yesterday. The wire is black but the manual says it's brown. It's also the wire to the WG controller which I don't use so it's open.

Looking at other brown wires this thing is not brown it's black. I disconnected the gnd at the back of the block and checked it to the o2, the ECM, etc. All checked. Put everything back together and the 2 sec fuel pump issue is still there. Put in my spare ECM and it works. Because the orig FP issue was intermittent it's difficult to tell if I really fixed it or not but that's the story.