Rough Starts

jay79cj7 · #1 (**permalink**) 08-12-2005, 01:41 AM

I can't figure this out, so maybe somebody can point me in the right direction. I've got a 79 CJ-7, 258 auto. Lately its been running real rough when its cold, and it seems like its taking longer to warm up. When I am at a stop, the idle speed dips far enough down that it runs rough and sometimes it stalls, below 500 rpm. If I tap the gas it goes back up, stays there for a few seconds, and then starts dropping back down again. As soon as I give it gas and start driving, its fine. It just doesn't maintain idle at a stop well. As soon as it warms up, it does just fine and idles without a problem. It has always behaved like this to an extent when it is cold, but it has never really done it much the summer. It is behaving like it does in the winter. I am used to it doing this right as the engine starts to warm up, but now it doesn't drive normally until its completely up to operating temp.

I am getting really sick of stalling right as the light turns green! Any advice?

Thanks,
Jay

CherokeeGuy42 · #2 (**permalink**) 08-12-2005, 11:31 AM

I was with a friend of mine last night in a CJ-7(4 speed) and it was doing the same thing. His oil pressure is dropping real low for some reason and idling hard, so he switched from a 10w-30 to 10w-40 and it helped fix the problem some, so he is looking at trying 10w-50 to see if that will help anymore. I think that he has a leak in the main seal and is causing his engine to not get as much pressure or something, so I don't know. If you figure out how to fix yours then tell me so I can let him know what might be wrong with his.

SeeJay · #3 (**permalink**) 08-12-2005, 11:51 AM

I've got the same problem with my '83 CJ7, also a 258/automatic. It takes a good 5 minutes or so for it to quit stalling when at idle and my oil pressure rarely climbs above 20 (assuming the gauge works fine).

I'm anxious to learn a little more about this myself.

-Jay

jay79cj7 · #4 (**permalink**) 08-12-2005, 12:30 PM

I think my problem is different from yours because my oil pressure is fine. It doesn't drop until the engine warms up and the oil thins out. Then its borderline, but seems to be OK.

By the way, I have the stock carter carb, but it is not the original. The previous owner put in a rebuilt one a couple years back and I really haven't had problems with it.

redrooster · #5 (**permalink**) 08-12-2005, 03:59 PM

I would say that it was the carb. Those Carters make great paperweights. It's probably got some major leaks or the choke isn't functioning properly.
Low oil pressure is common on CJ's. It has everything to do with the pump itself. If they were new engines I would be concerned. You can play with the types of oil to get the pressure to increase or change the pump out.

jay79cj7 · #6 (**permalink**) 08-13-2005, 12:40 AM

But why would it work fine when its warmed up if there was something wrong with the carb?

derff96963 · #7 (**permalink**) 08-14-2005, 09:39 AM

I would start by looking at the choke on the carb. If it is opening too quickly it will cause what you are describing. I need to adjust mine atleast twice a year. You have a summer and a winter setting.

redrooster · #8 (**permalink**) 08-15-2005, 03:48 PM

Quote:

Originally Posted by jay79cj7

But why would it work fine when its warmed up if there was something wrong with the carb?

Choke is malfunctioning or possibly the vacuum leaks are worse when the engine is cold. Metals expand when hot and might be sealing the leak.
Just some thoughts.

jay79cj7 · #9 (**permalink**) 08-15-2005, 11:44 PM

Thanks guys. I'll have to look into the choke and vacuum leaks. Now just to find time to do it...

exjay33 · #10 (**permalink**) 08-21-2005, 10:07 AM

Not the choke it is the jet for the idle is becoming plugged if it is a carter 1 barrel . there is an article step by step how to fix this problem at jeeptech.com , also the more they reformulate gas the more people with carbs are going to have fun.