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  1. #1

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    8hp Briggs updraft carb leaking fuel while trying to start.

    I've rebuilt this thing twice and it is clean with all new components. Needle and valve seat seal, all passages are open. once reinstalled, I turn the fuel on, takes some to fill the bowl and no more. If I let it sit overnight it won't leak a drop. As soon as I start turning it over the fuel starts to trickle out in a stream and stops a few seconds after I stop turning the engine over. It won't start, the plug stays dry so its not getting gas. If I can start it (spraying carb cleaner into the carb) it runs nice, WOT down to a even idle. This is driving me crazy!

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  3. #2

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    Re: 8hp Briggs updraft carb leaking fuel while trying to start.

    It sound like you must have a needle and seat problem or float problem. As soon and you put fuel pressure against the needle valve it is leaking by. Just go over all your steps when you put it together you must of missed something. Also watch your float level. Also when you mount the carburetor to the block make sure it is sealed good. What I do is take a flat diamond wet stone and smooth off the carburetor flange and block. You will be surprised how far it can be off. Also another thing to check would be your throttle plate shaft. I have found on that carburetor it tens to wear. As a matter of fact I just had to replace a carburetor this pass fall on a 8 hp briggs for that reason.

  4. #3

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    Re: 8hp Briggs updraft carb leaking fuel while trying to start.

    How could a wore throttle plate shaft cause fuel to leak out? I can see it causing it to run lean as could a leaking intake gaskets. I know (rationally) that it must be a leaking needle but I can't get it to leak any other way other than installing it and turning the engine over. Will tear down and try this a 5th time. (3x before I broke down and bought a kit.) Thanks for the reply.

  5. #4

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    Re: 8hp Briggs updraft carb leaking fuel while trying to start.

    Quote Originally Posted by mrfixit View Post
    How could a wore throttle plate shaft cause fuel to leak out? I can see it causing it to run lean as could a leaking intake gaskets. I know (rationally) that it must be a leaking needle but I can't get it to leak any other way other than installing it and turning the engine over. Will tear down and try this a 5th time. (3x before I broke down and bought a kit.) Thanks for the reply.
    I also thought you said that it wasn't picking up fuel to start by its self without priming it? Also them are things I do and check on all my carburetor OH's which is easy and not very time consuming. Not that it always happens but I try for a one time job. I have been there with the 5 time take apart. Some of the things I do to prevent that is I buy a kit right off, remove all soft plugs, sock in cleaner overnight, check for any vacuum leaks. I guess it gets to a point as to when you replace the carburetor?? I know that is hard to do when you have spent money on the old one. Hope you the best of luck Nick

  6. #5
    SONOFADOCKER's Avatar
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    If you take it apart again - soak the float in cleaner for 30 minutes . Remove it from the cleaner and shake it to see if you hear fluid inside the float ?
    Common that there is a little crack you can't see .
    Fuel shut off in the line would be best . Bad to keep gasoline in the bowl with the CRAP gasoline now .

  7. #6

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    Re: 8hp Briggs updraft carb leaking fuel while trying to start.

    sadly the float is fine. I've let it sit overnight a couple times and the needle doesn't allow any excess fuel by. Its as soon as it starts to turn over that the fuel floods out. Thanks anyway

  8. #7

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    Re: 8hp Briggs updraft carb leaking fuel while trying to start.

    Has it ever started while doing this??
    Is the intake valve stuck Open?
    Check the compression... KennyV

  9. #8

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    Re: 8hp Briggs updraft carb leaking fuel while trying to start.

    with the carb off; the machine will run by spraying carb cleaner in the intake. The problem is with the carb somehow.

  10. #9

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    Red face Re: 8hp Briggs updraft carb leaking fuel while trying to start.

    This is one of the most basic of carbs. Updraft carbs will drip fuel with full choke on a cold or any start for that matter. If the carb doesn't drip when the engine is not running and with the fuel turned on then is could be an over choking problem. My generator has the same carb and I usually cold start it with half choke and open it quickly after starting.
    These carbs can be damaged from incorrect dissassembly and what I mean by this is that the high speed nozzle must be removed first before the bowl can be separated from the carb throttle plate/ housing assembly.
    A too high float level will let fuel overflow thru the nozzle and drip. A leaking float needle and seat will do the same.
    Mad Mackie in CT

  11. #10

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    Re: 8hp Briggs updraft carb leaking fuel while trying to start.

    I reblt my 8 hp updft carb; and it willnot idle at all:done it all,What next?

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