1985 cj with idle and running rough

[1971jim0]

please help !!!!!!!!!! I HAVE A 85CJ WITH A INLINE SIX AFTER ABOUT AN HOUR OF DRIVING, THE JEEP STARTS TO SPUTTER AND BACK FIRE WHEN I COME TO A STOP IT DIES WHEN THIS HAPPENS IT SMELLS LIKE ITS RUNNING RICH. ANY HELP WOULD BE GREAT. IT DOES HAVE A NEW CARB INSTALLED A COUPLE OF MONTHS AGO

 

[Sasquach]

They did'nt have a V6 in 85.

 

[Cheepjeep85]

o2 sensor, computer going bad, vacuum leak, stepper motor going bad, coil going bad, ignition module, egr, distributor, etc. with the system that is used on these jeeps it can be damn near impossible to diagnose whats wrong with it. when it starts going bad, which they all eventually do most people start lookin for alternatives to it like, adapting to an mc2100, tbi fuel injection, mopar mpfi, then upgrading the ignition like using a chevy HEI, or ford TFI. we can help you try to diagnose it but i figure it'll be easier to solve your problem by telling you to replace it which, also, if you use a mc2100 and a ignition upgrade it'll possibly be cheaper and you'll get alot better performance and better fuel mileage than you ever will with the stock stuff.

there are also things you can do to the stock stuff to make it run better until you can afford to replace the failure prone stock equipment. try this it's a great write up on the "nutter bypass" http://www.jeepforum.com/forum/f8/how-nutter-bypass-522262/

 

[Sasquach]

Maybe start with the simple things like tune up parts like cap and rotor, spark plugs, timing, new fuel filter. there are so many things under the hood of an 85 AMC 258 i6 / 4.2l it's really out of my league. Best advise from me would be to get a FSM for your 85 and start reading and applying the info.

 

[mdmcintosh84cj]

i have a 84 cj that was running similar to that and the idle tubes were clogged up is it a carter carb

 

[KJs 83CJ7]

when it starts going bad, which they all eventually do most people start lookin for alternatives to it like, adapting to an mc2100, tbi fuel injection, mopar mpfi, then upgrading the ignition like using a chevy HEI, or ford TFI.

I've spent the last 3 days doing nothing but carb research, and it seems like all of my problems (that i'm aware of at this point) are carb related, and the only way to realy be 'happy' is to go fuel injection. I don't have the money now, but when I do, i'd like to do it right - i started looking at the mopar solution, but couldn't find it advertised specifc to an 83 cj. Does this matter? I found a great write up for a 90yj. Any help on where to find the right kit? Also, i had read that mopar cautions against installing it on a 'tired' engine. How do you determine this? The PO on mine said it was rebuilt about 5k miles ago.....? Cheers.

 

[Sasquach]

I've spent the last 3 days doing nothing but carb research, and it seems like all of my problems (that i'm aware of at this point) are carb related, and the only way to realy be 'happy' is to go fuel injection. I don't have the money now, but when I do, i'd like to do it right - i started looking at the mopar solution, but couldn't find it advertised specifc to an 83 cj. Does this matter? I found a great write up for a 90yj. Any help on where to find the right kit? Also, i had read that mopar cautions against installing it on a 'tired' engine. How do you determine this? The PO on mine said it was rebuilt about 5k miles ago.....? Cheers.

The Mopar works on all AMC 258 i6 / 4.2l engines, there are two diff kits one for man Transmission the other for auto Transmission . The system works amazing and well worth the money in my view.
mopar cautions against installing it on a 'tired' engine-I can't emagine they need to say that but if you have an oil burner with 200K that fouls plugs would you be spending 3K to upgrade the fuel system?
Sort of a common sense thing imo.

 

[KJs 83CJ7]

The Mopar works on all AMC 258 i6 / 4.2l engines, there are two diff kits one for man Transmission the other for auto Transmission . The system works amazing and well worth the money in my view.
mopar cautions against installing it on a 'tired' engine-I can't emagine they need to say that but if you have an oil burner with 200K that fouls plugs would you be spending 3K to upgrade the fuel system?
Sort of a common sense thing imo.

Good point...well taken...I found the kit, yeah; a bit pricy. What other things are 'must dos' and 'nice to dos' at the same time as this upgrade? Looking to minimize the amount of re-work will maximizing results. Thanks again.....

 

[Cheepjeep85]

a nice to do is a 4.0 head swap, rebuilding the motor if its like sasquatch said is a must do. if your motor is in good shape and you don't want to drop that much coin on it look into howell tbi their kits use a gm throttle body, i hear they work pretty well and only have about a $1,200 price tag. here is a link Jeep TBI Products - Howell Engine Developments, Inc.

 

[KJs 83CJ7]

Not being an engine guy, I ask....what kind is gained by changing out the AMC 258 i6 / 4.2l to a 4.0 on the AMC 258 i6 / 4.2l ? How much work is involved here?

 

[Cheepjeep85]

power and fuel mileage are the gains. its not to difficult sasquatch or thisguyuknow will be more qualified to help you than i am they have both done the head swap i havent yet. there is also alot of info on doing the swap on the site here and other places, its pretty well documented.