Carburetor problems - Impala Tech
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post #1 of 10 (permalink) Old 03-08-2020, 07:29 PM Thread Starter
Join Date: Dec 2019
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Carburetor problems

Hey guys, my 65 is not getting fuel through the carburetor. It’s a Carter Quadrajet four barrel. At first I thought my fuel pump went out, but when I removed the fuel line from the carburetor and cranked the engine over it was pumping plenty of fuel. Is it possible that the fuel pump would still pump fuel, but just not enough pressure to go in the carburetor? Is there a place where I can send my carburetor to be rebuilt?
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post #2 of 10 (permalink) Old 03-08-2020, 08:17 PM
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Check for a clogged fuel filter at the carb inlet. Use a good one inch open ended wrench and replace by thightening only by hand up to the final turn. Those thin threads pull out of the pot metal body very, very easily.

Big Dave
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post #3 of 10 (permalink) Old 03-09-2020, 08:07 AM Thread Starter
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I replaced the fuel filter and problem still persists. I even tried it without any filter at all and nothing changed.
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post #4 of 10 (permalink) Old 03-09-2020, 09:06 AM
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You can test the fuel pump with a large coffee can to measure the volume vs. time. Pressure is checked with a vacuum / pressure gauge.

I suspect that you may have trash in the carb if you had a paper filter that fell apart with gasohol. If so it will need a rebuild.

Big Dave
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post #5 of 10 (permalink) Old 03-09-2020, 03:10 PM Thread Starter
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I talked to a local carburetor shop, and I think I’m going to drop it off with them. I’m sure this carburetors never been rebuilt.
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post #6 of 10 (permalink) Old 03-09-2020, 03:46 PM
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I would still check out the mechanical fuel pump first. Ask if you can borrow an electric pump to see if your carb works with a constant fuel supply. If the problem is the pump just replacing it may not fix it. Reason being there is a steel rod riding on a cast iron eccentric sticking off the front of your cam. With today's motor oil being far to low in ZDDF to protect a flat tappet cam; it can also cause your fuel pump eccentric to go flat.

Most mechanical fuel pumps fail due to the diaphragm getting a hole in it. That is easy to see as there is a hole in the pump to allow the gas out of the pump before it gets into the motor oil in the oil pan.

Car repair gets to be real expensive real quick if all you are willing to do is to throw parts at the problem.The Service repair manual has pages of decision trees that allow you to go down the tree answering questions to find the actual problem. Might add that the Service manuals used at the dealership were written for certified mechanic. They expect a lot of knowledge and a goodly collection of tools in your tool chest. Another option is either a Motors manual, or a Chilton's manual specific to your car year. They were written for the shade tree mechanic and offer repair information in greater detail than just R&R. They also have illustrations and pictures of the repair instead of just text.

Big Dave
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post #7 of 10 (permalink) Old 03-09-2020, 06:57 PM
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Does it run when you pour gas down the carb?

Two doors, four doors, wagons, and ragtops.
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post #8 of 10 (permalink) Old 03-10-2020, 08:33 AM
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I echo some of what has been said. I would test the fuel pump pressure first. It is a bit difficult to diagnose without knowing if:

1. You are using the mechanical fuel pump and not an electric fuel pump
2. If the car will start and idle, but not run in drive or if it just doesn't run at all
3. Whether the car was running fine until this started or if we are resurrecting something that has been sitting for a long time

While a carb rebuild is not generally a bad idea, if you don't diagnose the problem thoroughly you may find your rebuilt carburetor still doesn't work. But it is possible it could be something as simple as your carburetor float sticking and not letting the car idle. In that situation, the float is not letting enough fuel into the reservoir to allow constant running of the engine.
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post #9 of 10 (permalink) Old 03-11-2020, 07:07 PM
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Quadrajet's were made by Rochester a division of General Motors. It is tough to diagnose without more information. Hope you figure it out.

66 Caprice Marina Blue 396 HD 3 Speed
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post #10 of 10 (permalink) Old 03-11-2020, 09:14 PM
Join Date: Jan 2019
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Your floats in the carb might be stuck in the bowl full position. This could be a problem with the needle and seat is a typical place for a binding of the two. If it is stuck in the full position it won’t allow any fuel to enter the carb. Start by removing t he lid and checking from there.
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