Chassis Ground isssues

[ParadiseMJ]

I have searched this but didn't find the answer yet.

 

I read up on chassis grounds since the PO had the bed off before I bought the MJ. I looked in the tail light bucket and found the ground in there less than OK so I shined everything up and tightened THAT ground up. Then by the fuel pump there is another ground (looks like ~12 ga. wire) to the frame rail.

 

Is there supposed to be another ground from the cab to the bed? Bed to the frame rail?

 

I'm trying to chase down the fuel delivery issue. I have NOT changed out the CPS. The FP relay is clicking away. I swapped it with a good relay from my XJ. Still no joy.

 

I have replaced the block to firewall strap with a 4 ga. cable, and an additional ground from neg post on battery to body. Headlights, tail lights, markers all work. Front blinkers, parking lights do not work.

[Pete M]

the cab and frame are one unit. the bed is bolted directly to the frame. far as I know there are not wires to connect grounds between those items.

 

Curious that you had a ground by the fuel pump. I added one in that spot on my 88 after I learned that my fuel pump was sucking its ground from that connection behind the tail light. :hmm:

[ParadiseMJ]

The FP ground looks as if it comes right out of the bundle. Looks stock!!?

 

The Black Widow webs all up in there have me a little worried, :eek: I'll have to spray for bugs and go back in there when it stops pouring. I'll put the new CPS in there and see if it clears up my probs.

[Wildman]

If you have replaced the ground strap from the fire wall to the rear of the engine, Good :thumbsup:

 

Check the ground (-) at the oil dip stick stud, there should be 2 additional, like 14 ga wires also connected to the stud. One of the wire is the ground to the ECU. If anything, add an additional ground wire from the mounting (steel) plate of the ECU to the stud, or even to the negative post on the battery.

 

I have seen a fuel pump problem with the ECU ground broken off :eek: Not properly grounded, it will not let the pump run, let alone let the engine spark.

 

As far as the black widows.............that's your problem :eek: Glad I don't have to deal with them up here :D

[glundblad]

I thought I remember the body mechanic telling me he couldnt get the truck started after he removed the bed. Then he figured out it needed grounded? I never found out specifically what he was talking about.

[CWLONGSHOT]

I have said it before but it bears repeating. Your on the right track checking and replacing your grounds. If in doubt of any REPLACE THEM. Too many is NEVER a problem!! Neither are EXTRA grounds!!

 

One other big one is the battery cables. I made my self a custom fit set with the correct cable ends and a big crimper made specifically for big cables. I for get the size I used, but its as big as your thumb and has very fine wires inside, the insulation is also quite thick. They where made for the medical industry in a X-Ray machine. MAN what a difference it made!!! the engine run smoother, started better and the lights are brighter as well!!

 

Good luck,

CW

[ParadiseMJ]

If you have replaced the ground strap from the fire wall to the rear of the engine, Good :thumbsup:

 

Check the ground (-) at the oil dip stick stud, there should be 2 additional, like 14 ga wires also connected to the stud. One of the wire is the ground to the ECU. If anything, add an additional ground wire from the mounting (steel) plate of the ECU to the stud, or even to the negative post on the battery.

 

As far as the black widows.............that's your problem :eek: Glad I don't have to deal with them up here :D

 

You were right about the additional grounds at the dipstick. When I pulled that stud at the dipstick I thought it was strange that there were 2 washers on it. Well, they weren't washers, they were ring connectors that had rusted/broken/corroded off. :doh:

 

I put a couple of crimp on 5/16" connecters on the 2 sets of 2 wires each. Polished up the stud and the block. The FP sprang to life, just like it should, on for appx. 3 secs and stopped. Got a good sqirt from the schrader valve on the fuel rail. :clapping: I'll put a gauge on there when I get one (payday tomorrow)

 

Still no spark though, so, I'll be doing the CPS (CKS)...wait for it...NEXT YEAR!!

 

Thanks for the help and suggestions.

 

***as far as the black widows, there are only 2 things that worry me around here...black widows and skunks.

[Wildman]

:thumbsup:

 

If your fuel pump ran for about 3 seconds, then that's what it's should do, once the pressure is reached, 31 psi with the vacuum hose connected to the pressure regulator, the pump will shut down, or stop pumping, until the pressure drops, you can just use a bunch of rags around the schrader valve, and push the needle down until the pump kicks on again, to double check that. If you go buy a fuel pressure gauge, check out the one Advance auto parts has, it also has the "flow" valve, with the tubing attached, it's twice the money than the one that leaks like a sieve from Harbor Fright is (experience speaking here :roll: )

 

http://shop.advanceautoparts.com/webapp ... RP2018____

 

Your NO spark would lead back to the CPS, or the wires, and/or connector.

 

CW's statement above is very true with these trucks, there mostly a "negative" contact system, that the more, added grounds, the better things work on them.