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Hard start and idle issue 4.2 carb

6K views 10 replies 4 participants last post by  My89yj 
#1 ·
Why won't my jeep high idle when started or at all for that matter. It also has an issue starting when cold. Fires over and stalls a few times. When it starts to stall I try to catch it and seems like it's loading up or not getting enough gas. After 5 or so times I catch it and hen it runs fine. But hasn't high idled in about a year. Is it fuel related( fuel filter, tune up) or just carb related
 
#3 ·
Your high idle on an 89 4.2 is mechanical. The spring in the auto choke housing might be busted. The linkage in and outside of the carb. could be hanging up. The first thing to do is to get choke and carb. cleaner and spray everything in and out real good.When cold, check to see if your auto choke is working by removing the air cleaner and manually giving the carb. full throttle to see if the butterfly on the carb. closes almost all of the way and stays there. If not you have a problem with the auto choke mechanism/linkage. If it seems like it's working check your choke housing on the left side of the carb. as you are looking at it from in front of the hood. Check to see if it's set on 1 notch rich. These carbs. seem to like to run on that setting. Loosen the 3 screws, don't remove them, set it to 1 notch rich after you cleaned everything and try it. The carb. might be shot at this point if it still doesn't work and needs to be rebuilt. The solenoid on the right side of the carb. activates electrically when you have the A/C on to slightly bump up the rpm's so you don't stall. If no A/C it also keeps the idle up when you brake hard and/or take your foot off of the gas to keep from stalling. This should be adjusted when the engine is hot.
 
#5 ·
I don't know to much about carve and am looking to broaden my knowledge so I appreciate the info. When checking the carb this is to be done befor I start up on a cold morning right and should I then check it another time after it's been run and still warm? And how do I know what 1 notch rich is? I also have had an issue in the past with my plastic idle cam getting stuck on 1500 rmp and remedied it but now it doesn't even seem to be engaging period is that also related to the choke?i havn't done a fuel filter since I bought it so I was wondering if that would be another idea for the issues? And if it is the choke I am assuming it can't be hooked up to a cable and operated manually?
 
#10 ·
You should definately replace your fuel filter anyway. Scott has some good advice regarding this carb. Before you start on anything consider the less complicated methods to fix the problem which might work. You may just have to clean the carb. to solve the problem. Start off with a can of carb. cleaner and then go from there. First, clean it in and out when hot and running then let it sit overnight. Before you start it remove the air cleaner and manually open the throttle and see if the butterfly stays closed. If it does open and close the throttle another 2-3 times to get additional fuel in there because these carbs. are known to leak internally. Then, get in, don't step on the gas and try to start it. It should go on a high idle. If not now you have to take steps to address the choke/carb. problem like Scott indicated.
 
#6 ·
yes the choke and the plastic cam work together.
the round black choke spring cover has notches marked in it for the 1,2,3 richness settings.
and yes i turned mine into a manual choke system because of the choke sticking issue that caused my mpg to suck.
and if you have not done the nutter by pass that is a must do.
it helps with cold starts, idling, lets the motor rev better and just plain run better.
give me a call if you need to ask anything while your wrenching on your JEEP.

http://www.jeepforum.com/forum/f12/picture-guide-nutter-bypass-476720/
 
#7 ·
yes the choke and the plastic cam work together.
the round black choke spring cover has notches marked in it for the 1,2,3 richness settings.
and yes i turned mine into a manual choke system because of the choke sticking issue that caused my mpg to suck.
and if you have not done the nutter by pass that is a must do.
it helps with cold starts, idling, lets the motor rev better and just plain run better.
give me a call if you need to ask anything while your wrenching on your JEEP.

This is a Picture Guide to Nutter Bypass - JeepForum.com
 
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