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  1. #1
    Join Date
    Feb 2020
    Location
    Moorpark, CA
    Posts
    22

    Default Carburetor leaking onto top of manifold after shutdown

    Hi all,

    I recently purchased a 1990 Carver with twin 454s. Port is Generation 4 and starboard is Generation 5.

    I exchanged the carb on the Gen 4 motor for a rebuilt one (the accel pump was not working on the original one). The rebuilt carb works great except it leaks fuel from the bottom of the carb after engine shutdown. There is no leak while running. The fuel accumulates on the top of the manifold, both front, right, and left sides. The engine has a mechanical pump. There was no leak with the old carb. It was just very hard to start since the accel. pump was not working and it has no choke.

    I took the carb back to the shop and he cleaned out the bowl and needle valve. He tested it and there were no leaks on the bench.

    I don't have the serial number handy right now. He assured me that it was the same model as the original carb but I am not totally sure if it is a marine or automotive carb. I will get the serial numbers.

    I have a thin gasket between the carb and manifold, similar to the oem Crusader gasket.

    Ideas?

    Thanks!
    Barry

  2. #2
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    8,272

    Default Re: Carburetor leaking onto top of manifold after shutdown

    There is really no leak path "out the bottom of the carb" except for the throttle shafts....and they aren't wet in normal operation.....

    My guess is the fuel pump diaphragm has failed and the resulting fuel is going thru the sight tube into the primary bore on the carb. This is supported by the "no leaks on the bench" above.

    without knowing the condition of the Tygon tubing, the best thing would be to inspect the primary bores to see if the fuel is being dumped in.

  3. #3
    Join Date
    Feb 2020
    Location
    Moorpark, CA
    Posts
    22

    Default Re: Carburetor leaking onto top of manifold after shutdown

    Thank you! I will check it out this weekend. I will also measure the fuel pressure while cranking.

    Barry

  4. #4
    Join Date
    Sep 2008
    Location
    pensacola, fl, us
    Posts
    217

    Default Re: Carburetor leaking onto top of manifold after shutdown

    Just had my carbs rebuilt by Cliffs High Performance. (great job). When Cliff sent my carbs back, he included the THICK intake to carb gasket.

  5. #5
    Join Date
    Feb 2020
    Location
    Moorpark, CA
    Posts
    22

    Default Re: Carburetor leaking onto top of manifold after shutdown

    I cleaned the blue paint off the sight tube so I could see inside (prior owner!!). The tube is dry.

    I ran the boat for over an hour yesterday at low speed. It ran beautifully and there was NO LEAK after shutdown! Maybe the new needle valve and seat had to settle in?

    I checked the temperature of the carb with a laser temp gauge just after shutdown. The intake was about 144 deg. and the carb was 104. So, not too much heat soak.

    Thanks Kevin for the tip about the thicker gasket. The guy who sold me the carb also gave me a thick one but my studs are not long enough to accommodate it. I can always get longer studs if needed. Did you get a 4 hole gasket an open gasket? My intake manifold has 4 holes to match up with the carb barrels so I went with a gasket to match the carb bores with the intake.

    The guy at the carb shop said to maybe lower the float height a small amount if the leak continues.

    I will monitor for leaks for now.

    Thanks!
    Barry

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