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.

I want to say fuel, but you've already replaced the fuel pump and filter? Bad gas? I know its been in the news lately...

If you can rule out your vacuum hoses and fuel pump, make sure the ignition coil is delivering a strong spark and double check ignition timing. That's where I would start.

Its a long shot but a plugged cat can cause wierd symptoms like this, the chunks move around so the problem can come and go.

old_man said:

Its a long shot but a plugged cat can cause wierd symptoms like this, the chunks move around so the problem can come and go.

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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?

no check engine light? cleaned the carb? make sure your dist cap is tight moisture is a mf on the ignition system. you'll just have to start with the basics man

Squirt a little oil behind your IAC, piston and see what happens. Look at the air filter, any cotton wood trees around? Check the MAP vacuum line for a rub through, someplace. Pull the vacuum line off of the EGR valve and plug it, see what happens. A few possibles.

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.

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.

AngryDog said:

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.

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.

Click to expand...

The ballast resister cuts the voltage to your fuel pump after the engine is running, to make the fuel pump run quieter. You can usually bypass it safely if its giving you problems. My jeep doesnt have one anymore.

AngryDog said:

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.

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.

Click to expand...

Actually it will start without it, but won´t run for long (most times). When your starting, the starter steals a lot of juice, the resistor is bypassed, the pump runs at full available voltage/amperage (watts). After it has started (running), the power to the pump runs through the resistor to cut the voltage back down some. The pump is designed to work at the lower voltage/amperage,which is typical for the starter sucking the system down some.
ECU does pretty close to the same thing, gives it a little more umph at start.
I didn´t know a balast resistor would do what you described, if it shorts and the coil inside melts together it actually has less resisitance. If it melts open, it probably won´t run (for long). Maybe you were getting a little voltage from a strange path, the wrong way through the harness? Darned if I know.
Maybe the resistor coil melted part way through and increased the resisitance.
I tied a jumper wire, right next to my balast resistor, just in case. Had one pop like a firecracker, after splashing it with water (mud) which blew the back off of it.