Fuel dribble from venturi under acceleration - Hot Rod Forum : Hotrodders Bulletin Board
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Old 05-26-2013, 12:53 PM
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Fuel dribble from venturi under acceleration

Working on a 1930 ford street rod with a 260 hp 350 Chevy engine and a Holley 4150 4 barrel carb with mechanical secondary . Carb and fuel pump is 6 years old and has always worked fine. Stock mechanical fuel pump and one filter before the pump and one filter before the carb.

Out of the blue, I am getting gas dribbleing from one venturi, only when you accelerate, which causes the car to run ruff. Idles fine. Only does it when you accelerate.

I took the front bowl off to inspect the float and it was fine. Blew it out with compressed air, installed a new needle and seat, lubed the 0 ring, and adjusted the fuel level to just under the sight glass per Holley's directions.

That did not change a thing. I still have gas dribbleing from one venturi when you accelerate. I haven't done any work to the car prior to the problem. Also tried lowering the fuel level a bit with no success.

Don't have the equipment to check fuel line pressure. Is it possible for fuel line pressure to increase with a mechanical pump, out of the blue for no apparent reason after it has been running OK for 6 years?

Any idea what is causing this? Thanks for any ideas.

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Old 05-26-2013, 03:44 PM
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You won't know until you put a 0-15 psi mechanical fuel pressure gauge in the system and run it up to the cowl, where you can see it through the windshield as you drive. 5 psi max for Carter, Edelbrock and Rochester. 6 psi max for Holley.
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Old 05-26-2013, 09:21 PM
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Fixed the venturi flooding problem!

I have fixed the problem but really don't know why. If anyone has an explanation, I would like to hear it. There are 4 small holes in front of the venturi, I assume they are some kind of vent. I blew compressed air into each one of these holes, fired up the motor and it ran like a new car, problem fixed. In an attempt to keep trash out of the carb in the future, I found and replaced a bad gasket between the air cleaner and the carb, and I also replaced the elcheapo fuel filter with a 40 micron unit that Holley recommends.
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Old 05-27-2013, 06:13 AM
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Quote:
Originally Posted by HotRodMan View Post
I have fixed the problem but really don't know why. If anyone has an explanation, I would like to hear it. There are 4 small holes in front of the venturi, I assume they are some kind of vent. I blew compressed air into each one of these holes, fired up the motor and it ran like a new car, problem fixed. In an attempt to keep trash out of the carb in the future, I found and replaced a bad gasket between the air cleaner and the carb, and I also replaced the elcheapo fuel filter with a 40 micron unit that Holley recommends.
You had a clogged air bleed.
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Old 05-27-2013, 11:10 AM
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Watch the video.

https://www.youtube.com/watch?v=2VOXXRtyG3E
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