HELP I Need HELP

OK here is what I got. I bought a 89XJ 4.0I last fall went through the whole thing mecanically, plugs, rotor, wires, cap, cold air intake, IAC cleaned, CPS, MAP sensor, all new vac hoses, fuel pump and filter, battery and cables, cleaned the carb and a lot of other stuff. It has run like a top until about two weeks ago. It started to run almost like it was skipping but I don't think so. I was only doing it when I was going uphill until yesterday. Today I take it into town and it ran pretty good. Then this after noon I was helping out a bud and it was like shit. Chugging almost to the point of stalling. WHen I got it moving some and increased the gas quiet a bit it seemed to smooth out some. But I still could feel it chugging a bit. Parked in the drive until tommrow. Any ideas my fellow XJers? Ialmost seemed today to be not getting fuel, but when I increased the throttle it smooths out quiet a bit. Then back to chugging at low speeds. Give me some ideas where to start looking.

Maybe some bad gas, or your cat is clogging. Since you replaced everything else. Seems to run better if you give more throttle, starving for fuel, or cannot breath (cat).

My .02

Swabe~

macs97XJ said:

Maybe some bad gas, or your cat is clogging. Since you replaced everything else. Seems to run better if you give more throttle, starving for fuel, or cannot breath (cat).

My .02

Swabe~

Click to expand...

Thanks but I forgot to mention I also changed the exhaust from the manifold all the way back, including the cat and O2 sensor. Anymore info?

Next time it does it - jump the resistor on the fender above the air box (fuel pump resistor) with a 2" piece of electrical wire with stripped ends pushed into the terminals on the two orange wires. Heat and age will cause the resistor to fail (ask me how I know!). Or just change the resistor (about $4 at AZone)

Thanks for all the help and ideas. After a scary trip into town for a doctors appoinment, dam thing started up again, chugging, backfire, and stalling. So much so the muffler overheated and caught the rug liner on fire. Then I went to NAPA and got new plugs, wires, cap and rotor also seafoamed her. Swapped them out all to no avail. After seeing a couple of posts on it could be the ballast resistor. Jumped the thing and viola, it run like a top again. Took it to town and got a new one. Back in bussiness.

Sould have read this post before buying all the goodies.

Question:
Just what does that thing do? I new it didn't start wothout it but I did not know it could make a viechle run like that.

The fuel pump balsat resistor cuts the 12V (cranking voltage on starter) down to 8?V after starting for normal running. If the resistor is bad the Jeep will start on key but quit when the key goes to normal run position. If its intermittent (as usually happens) it gets worse with underhood heat.