too lean too rich
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Fleet Owner
Joined: Jan 2004
Posts: 26,007
Likes: 575
From: Brentwood,CA
too lean too rich
i am trying to work on a odd carb problem the truck won't idle unless the choke is applied 3/4 of the way and with the choke closed it pulls 21 in vacuum but take the choke off and the engine drops to 10 vacuum and dies what is the problem here.
Senior User
Joined: Jul 2004
Posts: 142
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Sounds like you have a major vacuum leak somewhere. Make sure all you extra ports are closed. If you have a vacuum pump, check the vacuum lines and accessories. I just found a bad vaccum advance today, sucker is a wide open vacuum leak. Nothing that required the choke like yours.
The other thing is that the carb could be way too lean. What carb are you running and have you made any recent changes?
The other thing is that the carb could be way too lean. What carb are you running and have you made any recent changes?
Thread Starter
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Fleet Owner
Joined: Jan 2004
Posts: 26,007
Likes: 575
From: Brentwood,CA
the carb is a almost new out of the box holley 4160 600 cfm carb it ran ok when i first put it on but now i am thinking vacuum leak there is only 3 vacuum hoses on my truck trans brake booster and distributer i will go out and check
Moderator
Joined: Dec 2001
Posts: 22,436
Likes: 17
From: Louisville,Ky.
Spray around the base of the carb and where the intake meets the heads with carb cleaner and see if it changes the idle. If not, then you may have a piece of debris in the idle circuit of the metering block.
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Fleet Owner
Joined: Jan 2004
Posts: 26,007
Likes: 575
From: Brentwood,CA
thats the problem it won't idle at all it will only work with the choke applied and the fast idle at 2,000 once you tak the choke off it dies won't even try to idle i took it apart and it is pretty clean but on the mounting gasket i noticed what looked like fuel marks on the gasket and the back carb stud was not tight could this do it
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Junior User
Joined: Sep 2004
Posts: 68
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From: washington!
I would say that a loose carb stud could cause a pretty big vacuum leak. I would replace the gasket and torque the carb bolts to spec. The gas marks are likely from all the fuel being dumped into the motor when you have the choke on.
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