GraniteChief

So I welded to my roof rack last night...at about 10pm, outside in the snow in 20F weather in a short break between snow flurries. It was about the umpteenth time I've welded to my Jeep. I disconnected the battery and ECU like I always do, finished welding, hooked it back up, and no start. It cranked fine, I could smell fuel, I could hear the pump, but it would not start. No codes, but O2 and a few other smog categories were flashing. I fried an ignition coil once when I shorted the battery to the block so I replaced the coil thinking maybe I fried the coil. Still nothing. I checked all fuses and relays. They were fine. I bypassed the alarm, still no start. I swapped ECU's, still nothing, so I put the old one back in. At midnight I crawled under the Jeep in the snow and replaced the crank position sensor with some very cold hands. Still no start.

It was 2am at this point and I was about out of ideas, and I needed to get up to leave for work in 6 hours, so I sat there trying to start it and pushing on the gas pedal. Well, it fumbled. I tried again and it started, but ran very rough and the idle went from low to high then finally settled on a normal idle after a minute or two. It acted like the IAC was out of whack. Turned it off, started it again no problem. The fuel gauge now reads overfull even though it has half a tank though.

I don't get it. What happened? All I can think of that went differently this time is I had bad ground on the welding clamp at first and had to reposition it. Maybe the welder charged up the Jeep's ground like a capacitor? I've had bad grounds on my welding clamp before though. Could this have caused the IAC to close and fried the CPS when the battery and ECU were disconnected?

I'm planning to take this Jeep desert camping in the snow soon...very, very far away from the highway. I'm nervous guys. Does any of this make sense? What happened to the Jeep? Any idea why the gas gauge doesn't work now, or how to fix it?

doublechaz

Just a WAG, but perhaps you burned a hole in the carbon track for the variable resistor in the fuel level sender and the throttle position sensor. Perhaps beating the pedal rubbed off the contacts so there is only a tiny hole and the rest of the sweep works. If that is true perhaps a few tanks of gas and some bumpin around will get the fuel level sender mostly working as well. It would take some time with a multimeter to do some testing if these ideas are really true.