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Unread 06-07-2013, 08:06 PM   #1
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1990 yj 4.2

Question for the carburetor masterminds. My 1990 Yj 4.2 is having trouble idling. I have already done a few simple things to correct this but I am not having any luck. I tried raising the idle, adjusting the gas/air mixture, and also preformed the "nutter bypass," but yet every time I stop at a stop sign or traffic light, the engine will stall.. My next move is to adjust the choke, and possibly replace the float in the carb. The carb has been rebuilt not even 200 miles ago. I have 163k miles on the 4.2 and it runs great, great pick up, great acceleration, and runs great at a steady speed, but like I stated before the only problem is it wont idle. Any ideas please let me know, thanks

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Unread 06-07-2013, 08:29 PM   #2
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1990 CJ7 
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Have you done this yet? A must do with gasahol today.
418 miles on 19 gallons of gas. Can't beat the BBD !
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Unread 06-07-2013, 10:40 PM   #3
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1999 XJ Cherokee 
Join Date: Sep 2004
Location: Salt Lake City, Utah
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I had that issue with my carb a few weeks ago I had to replace a vaccum line and adjust the idle speed, and bump the timing it runs smooth as silk now !
'89 YJ The Smurf Build Thread
'99 XJ Black Betty Build Thread
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Unread 06-08-2013, 09:02 AM   #4
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I had a slight leak in my egr valve and another in my brake booster that caused my 4.2 bad idle issues . I would do a very thorough check of gaskets and such for vacuum leaks
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Unread 06-08-2013, 10:13 AM   #5
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1987 YJ Wrangler 
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Location: Raleigh, NC
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Clean the idle tubes if you haven't already.
probably out breaking stuff.
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Unread 06-08-2013, 12:27 PM   #6
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1990 YJ Wrangler 
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Location: Mazomanie, Wisconsin
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+1 on pulling the venturi and cleaning the tubes
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