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truemainer150 04-10-2008 05:19 PM

4.2 rough idle and stalling problem
i have a 1990 yj 4.2 with a weber carb which had always had a hard time starting and every once in awhile it would stall when down shifting. it idle rough when its cold out (barley running) but once warmed up its fine. the other day i took it out mudding and must have sucked up something because when i would let out the clutch and push on the gas it would stall as a started to move. i rev'd it up and it backfired a few times and the stalling right after i let off the clutch went away( at the time i just wanted to get it home) but now it will start but when i shift the rpms drop and it stalls it also stalls when i stop. so it only idle when its first start and i have to help it out by giving it some gas until it takes and idles but it is barley idling. it also still starts hard in the cold. Any ideas of what it is?
{note it doesnt have a cat could water been sucked up the pulse are tube? i have heard this to be common. i though some dry gas and in tank gas cleaner but no change yet.}
any help would be greatly appreciated
thanks, Ethan

jpdocdave 04-10-2008 05:25 PM

thats no fun, fuel injection is nice.

truemainer150 04-10-2008 05:51 PM

yeah its not so fun and fuel injection is very nice...any ideas of what it could be?

The Sos 04-10-2008 09:57 PM

Mine does roughly the same thing as far as starting (I also have a 4.2 with a Webber carb). Everyone seems to want an arm and a leg to adjust the Carb or rebuild it so I thing I am going to save for the fuel injection kit. Its more in the long run but I have read that its well worth it. Hope you didn't suck something in your engine.

truemainer150 04-11-2008 03:03 PM


ctclark1 04-11-2008 06:20 PM

Closest I had to this problem was when I sucked a piece of hay chaff into the carb and it blocked one of the jets - engine would run fine at idle, and seemed okay at high rev, but right in the power band it would sputter and spurt... Took the carb apart, found the chaff, put it back together and it ran like a charm.

truemainer150 04-11-2008 08:47 PM

could a fouled plug do this or water in the distributer? could i maybe have fouled a plug wheeling? it sat all for most of a winter but that was two winters ago. let me know if i can provide you whit some more info.

ctclark1 04-11-2008 11:01 PM

choke adjustment? broken choke spring? Idler adjustment? I'm not the best trained engine guy in the world but it probably could be any of those, too.

truemainer150 04-12-2008 08:38 AM

we took the electronic choke out thinking that was the problem and installed a hand choke....where about is the idle adjust spring on a webber carb for a 4.2? should i try to mess with the idle? i know how to adjust it and make it right i just dont know where the idle adjust screw is. thanks.

ctclark1 04-12-2008 06:10 PM

Not sure on a Webber carb - Mine was replaced with a Motorcraft/Holley carb when I bought my 87.
(And, ooo, a fancy electric choke... I mentioned the choke thinking you had a bimetallic spring choke)

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