Cars House

85 cj7 with the 258- starts up, and even after warming up a bit, when i go to drive, it hacks and dies. takes a while to start, but does eventually, and then dies again. after about 10-20 minutes, it drives fine. i took off the air cleaner and smoke was coming out of the carb. i originially thought this was an electrical problem, but all the wiring and components were checked. could it be possible that after 130k miles the carb just needs to be rebuilt, or should i just throw in a weber? if i had the money i'd put in a something with efi, but i don't-
The rebuild kits run about $20.00 and do them wonders.

The choke linkages need cleaning, especially where the electrical heater's pin is.

To see if the choke is at least trying to work, on a cold off engine, take off the air cleaner and give it one shot of gas. The choke should pop closed. Then start it up after a second shot of gas and watch the choke. It should slowly open as the engine speeds up to 1750 rpm, then it drops the engine speed to 1250 or so, then it drops the speed to 1000 or so then it goes to idle when it is all the way open.

Watch the fast idle cam with it's steps. If it hangs on a step, a shot of throttle is sometimes needed to lower the speed to the next step down. A nice clean perfect system should only need the shot of gas to get off the high step usually. The choke is supposed to be able to pull it off, but...
Mine did the same, and I put a rebuild kit in it. It runs fine now.
thanks- it's not stepping down like it should, even with the gas. are they easy to rebuild?
thanks- it's not stepping down like it should, even with the gas. are they easy to rebuild?

Yes, just take your time and don't open or unscrew or unadjust anything unless you have to. The float and the accelerator pump will need to be set back up. The kits have good directions.

You also should clean the U shaped gas line between the filter and carb. An amazing amount of crud can collect in that and get knocked loose to go right back into the fresh carb.

Pay close attention to the center pin of the choke assembly. It gets corroded easy and can be a reason the choke plate isn't pulling back strong to get the fast idle down.

When open, you might want to ream out the idle pickup tube ends. It is a recommended mod by AMC even I was told. They should be made 0.032" so they don't act as a log jam and block up so easily. Here is an article about it:
http://jeep.off-road.com/jeep/article/articleDetail.jsp?id=277064

The tool can be found at welding supply stores.
You might have some gunked up linkages as well. Spray the heck out of it with a can of carb cleaner and then work all the linkages by hand. They might free up a abit.