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  1. #1

    Default 15 hp carburetor flooding after rebuild

    I have a 1996 15 hp Johnson that was running a bit rough so I bought a carburetor rebuild kit for rebuild. Cleaned the carb, blew out all the ports with compressed air, rebuilt it and replaced it in the motor. Now it won't start and gas floods out the top side port when attempting to pull start the engine. Have taken it back off, checked to make sure the float is free and the needle and seat centered under the float arm. Have done this repair several times before with no problems. Not sure what I missed this time.

    Any help appreciated!

    domer7

  2. #2

    Default Re: 15 hp carburetor flooding after rebuild

    did you set the float level correctly? New needle and seat?

  3. #3

    Default Re: 15 hp carburetor flooding after rebuild

    Quote Originally Posted by domer7 View Post
    I have a 1996 15 hp Johnson that was running a bit rough so I bought a carburetor rebuild kit for rebuild. Cleaned the carb, blew out all the ports with compressed air, rebuilt it and replaced it in the motor. Now it won't start and gas floods out the top side port when attempting to pull start the engine. Have taken it back off, checked to make sure the float is free and the needle and seat centered under the float arm. Have done this repair several times before with no problems. Not sure what I missed this time.

    Any help appreciated!

    domer7
    It is a new needle and seat. Did not adjust the float at all.

  4. #4
    Join Date
    Jun 2013
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    Duluth Mn
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    Default Re: 15 hp carburetor flooding after rebuild

    Set float so it shuts fuel flow when it is parallel with the carb float bowl surface. Best to flush out lines and fuel pump/clean the screen, as well as replace all hoses at the same time. Ethanol will damage rubber hoses, diaphragms, etc. over time. There could be debris getting into the needle/seat area and causing this symptom.

  5. #5

    Default Re: 15 hp carburetor flooding after rebuild

    Take the float bowl off and hold the carb upside down. Now set the float so it sits level to the carb body. Some of the new needles are a little shorter than the older ones.

  6. #6
    Join Date
    Sep 2010
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    17,807

    Default Re: 15 hp carburetor flooding after rebuild

    There should be no need to " rebuild " a carburetor every few years.----What other trouble shooting has been done if any ?

  7. #7
    Join Date
    Jun 2013
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    Duluth Mn
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    Default Re: 15 hp carburetor flooding after rebuild

    Racer, maybe Domer means he has done carbs before, (perhaps on other motors). Certainly carb work is a once in 10 or 20 year job. The twin 30's in my picture above are originals from 1986. Carbs NEVER been overhauled.
    Last edited by timguy; 11-20-2019 at 03:08 AM.

  8. #8

    Default Re: 15 hp carburetor flooding after rebuild

    How do you keep sludge from building up in tiny orifices and jets? I've diasembled carb about every three years and blown out all the jets and orifices. Runs much smoother when re-installed.

  9. #9

    Default Re: 15 hp carburetor flooding after rebuild

    Quote Originally Posted by domer7 View Post
    How do you keep sludge from building up in tiny orifices and jets? I've diasembled carb about every three years and blown out all the jets and orifices. Runs much smoother when re-installed.
    Make sure your tank and line are in good condition. Run a fuel system cleaner with every tank.

  10. #10
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    Default Re: 15 hp carburetor flooding after rebuild

    Right on Mr. Scott. I won't mention the effects of ethanol, however.....seeing your in the same thread.

  11. #11
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    Default Re: 15 hp carburetor flooding after rebuild

    When you are done boating run the carburetor empty.------No fuel in the carburetor and it won't gum up and it passage ways / jets stay clean !!

  12. #12
    Join Date
    Jun 2013
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    Duluth Mn
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    Default Re: 15 hp carburetor flooding after rebuild

    That's correct, Racer. Also run full choke as it starts to die. That will slurp the last of the mixture out. For seasons end, I also pull 'em over a few more times and often get a pop or two. Since I often run 100:1 Amsoil, I then "fog" with oil, apply choke, then pull over another 5 or 6 times. My little 6 hp Fisherman 1965 model has only needed one carb cleaning in 54 years. Use it every year. Don't you love mice? This is a 75 Stinger, needed all carbs cleaned. Click image for larger version. 

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    Last edited by timguy; 11-21-2019 at 07:26 PM. Reason: Add info

  13. #13

    Default Re: 15 hp carburetor flooding after rebuild

    Quote Originally Posted by timguy View Post
    Right on Mr. Scott. I won't mention the effects of ethanol, however.....seeing your in the same thread.
    You should mention the cleaning effects of Ethanol. Just don't use the gray fuel hose with it. I use 10% ethanol in all my outboards keeps the fuel system squeeky clean.

  14. #14
    Join Date
    Jun 2013
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    Default Re: 15 hp carburetor flooding after rebuild

    True Mr. Scott, when properly managed it HAS some benefits. You probably live in an area where you operate your equipment regularly and consistently as well as using additives. Storage off season in damp places like Minnesota can be a challenge. Alongside of my non oxy use, I also recommend additives. Your advice is well received.

  15. #15

    Default Re: 15 hp carburetor flooding after rebuild

    Quote Originally Posted by timguy View Post
    True Mr. Scott, when properly managed it HAS some benefits. You probably live in an area where you operate your equipment regularly and consistently as well as using additives. Storage off season in damp places like Minnesota can be a challenge. Alongside of my non oxy use, I also recommend additives. Your advice is well received.
    I live in WI.

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