Engine Not Turning Over!!!

[mattk85c]

Okay guys, here is a problem for all you troubleshooting electrical experts out there:
I did a pretty good bit of welding on the passenger side body mounts on my jeep the other day and when i got done the jeep wouldn't crank. when i turn the key over to start it, the starter doesnt turn the motor over. i checked the starter with jumper cables and it works and with the switch on, the jeep runs as long as the jumper cables are connected, but once i remove the cables the motor cuts off. i thought it might be the solenoid, but i ohmed it out according to my jeep service manual and it passed. also when i turn the key i can hear the "plunger" in the solenoid kicking over like it should sound. so to me the solenoid is getting activated and the starter works, so i have no idea why the jeep wont crank. i have had no problems before this, with the motor. i rebuilt it 6 months ago and redid most of the wiring from the firewall to the motor. i feel like welding was the problem, i didnt think to disconnect the battery, but i dont know what i could have messes up. does anybody have any suggestions? any help would be greatly appreciated. thanks, -Matt

[AMX69PHATTY]

Ground wire / strap between block and x-member on pass side still inplace and intact ?

[mattk85c]

im not sure if i know what wire you are talking about and i dont think i even had that ground wire connected before. the battery is grounded to the body. i dont think the engine is directly grounded to the frame.

[tufcj]

Ideally, the battery should have a heavy ground to the engine, then there is a heavy gauge ground from the block to the frame (factory was about a 6" long wire across the passenger side motor mount). There is then about a 10 gauge wire from the negative battery post to the body. The solenoid needs a good ground to the fender.

Sounds like you have a ground problem. The welder may have burned out whatever was working as a ground, depending on where you had your ground lead attached.

Bob
tufcj

[mattk85c]

i looked in my service manual and it agreed with your advice. i will make these changes in the morning. i hope grounding is my problem, but the jeep was running good before. another question about the solenoid... since i hear the "plunger" activating, does that mean it is working properly? are there any other ideas about what could be the problem? thanks for yalls advice, i will let you know what happens.

[401 Pacer]

I totally agree with what others have already said.

A quick and easy check to verify if this is the problem would be to take a set of jumper cables and hook ONE cable to the ground on the battery and the other end of the SAME cable to somewhere on the engine (make sure you make contact thru any paint etc).

LEAVE THE OTHER CABLE UNCONNECTED

Then try cranking it again. If it works, then you have your answer: open ground circuit to the engine.