Q jet problem
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Instructor
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Q jet problem
why would my q jet squirt from the jets connected to the accelerator pump on their own without me pumping the gas while the car is not running and it is warm? it is creating a flooded situation and is not fun
Tech Contributor
Joined: Aug 1999
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From: At my Bar drinking and wrenching in Lafayette Colorado
It's rare for the Q-Jet to have this problem - this is usually a Holley issue with the bowls that hang out over the manifold. The problem can be corrected on both Q-Jets and Holleys by using a reflective heat shield between the carb and the manifold.
This assumes that you are using the correct gasket between the manifold and the carb - you didn't state what year your car is. If you have the early-style intake with the "smiley-face" exhaust crossover, you have to use a special 3-piece gasket set to prevent the hot exhaust gasses from boiling the fuel in the carb.
Lars
This assumes that you are using the correct gasket between the manifold and the carb - you didn't state what year your car is. If you have the early-style intake with the "smiley-face" exhaust crossover, you have to use a special 3-piece gasket set to prevent the hot exhaust gasses from boiling the fuel in the carb.
Lars
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Thanks, my car is a 81 with 319,000 on the clock, this is a daily driver and i have been running this carb for the last 7-8 years with no problem always using Chevron Mid Grade, so i am not sure why all of a sudden this has become a problem, if just replacing the gaskets is the answer that would be great?? I pulled the aluminum manifold off a long time ago when i stripped the threads have been running cast iron for about 15 years now
Team Owner
Joined: Jan 2006
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From: Crossville TN
Might be due to the amount of ethanol is being put in your fuel now. Refineries can vary the amount based on time of year and production costs. Sure sounds like a fuel 'perk' problem. The cast iron manifold would also hold more heat than the aluminum unit.
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I can't imagine that they have added that much ethanol as of late, this seemed to come on quickly, I have been running a heavy amount of carb cleaner and it seemed better today, just odd as this has never been a problem before
Burning Brakes
Joined: Oct 2008
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From: Mobile Alabama
Spring is a good time for percolation. Fuels are blended differently for cold weather, and a tank of winter fuel plus warm weather can be a cause. If you are adding "stuff" to the fuel to clean the carb, you may be adding to the problem. Not sure of your exhaust or intake, but the exhaust crossover, and/or heat riser valve could also help overheat the fuel.
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Burning Brakes
Joined: Oct 2008
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From: Mobile Alabama
If what you say is happening, it doesn't sound like you need to rebuild. It sounds like the fuel is boiling. This could be the result of several different things - or a combination of things. But dont take my word, you had Lars above giving you some information, and he is the exalted guru of the Qjet. The shield he mentioned was in the link I put in you other general thread.
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If what you say is happening, it doesn't sound like you need to rebuild. It sounds like the fuel is boiling. This could be the result of several different things - or a combination of things. But dont take my word, you had Lars above giving you some information, and he is the exalted guru of the Qjet. The shield he mentioned was in the link I put in you other general thread.
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From: At my Bar drinking and wrenching in Lafayette Colorado
Lars
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Thanks for the input Lars, hopefully this will correct itself else I will have to look into your suggestions above or try my hand at rebuilding the original carb I pulled off, hopefully someday soon I will be bolting down the FIRST TPI injection unit that has been on the shelf for the last 10 years
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Melting Slicks
Joined: May 2007
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you have to take off the carb top and remove the float to get to where it goes on top of the check valve ball bearing. it puts more pressure on the check ball bearing to hold it in place
Last edited by PAmotorman; Apr 5, 2015 at 05:17 PM.