90 740 Injector ground source

[VABCHMECHANIC]

I've got a 90 740 here that has problems starting. The problem stems from the injector ground. Car wouldn't start. Would start with starting fluid. I verified that the fuel rail was getting pressure. Tested injector with noid light. Nothing. Then I checked each terminal of the injector plug with a test light. Getting a constant positive. While the light was still connected to the ground of the battery, I checked the negative side of the injector plug. It gave me a light spark and then lit up dimly. Tried starting it and it ran. Injector ground weak, though. Ran for a couple minutes and died. No start. I toughed the test light again to the negative side of the injector plug. Got a little spark. Car started up again. WTF?
It seems as though there is a ground issue either in or to the computer. When I touch it with my test light, the ground feeds through and gives it some sort of jump.
the reason why I'm posting this is to see if I can get help determining the source of my problem. I don't want to get a computer if it simply has a bad ground wire somewhere. I don't know where the computer is. I don't know where the original source of the ground is that goes to the injectors. If I can test the incoming ground to the computer for these injectors, I can make a proper diagnosis.

[russellengineering]

Hi Vabchmechanic,

There is an injector ground right under the fuel rail which could be the culprit according the the info I have read before.

Look under the rail and you will see 1 or 2 wires that are connected to the intake manifolds with a small bolt. The bolt could be loose, the connection dirty or corroded, or and this is the one that seems to get folks, the crimped connector loses tension and loses continuity erratically. The Brickboard site discusses this in "fuel injection" which is where I got smart about it. They discuss taking it apart and resoldering the connection on the crimp connector.

My 940 has 2 connectors under the fuel rail which i have been maintaining, you might just have 1.

Good luck,

Dave

[Fred760DC]

This corrosion problem will not trip a trouble code. DeOxIt cleaner removes crud INSIDE crimp on lugs (Which you should still solder on, as the crimping is not vibration proof) Regular electrical/brake cleaner willNOT remove corrosion inside the lug.