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help with small engine repair

Discussion in 'Off Topic Threads' started by SPACE GUN, Oct 8, 2011.

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  1. SPACE GUN

    SPACE GUN Member

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    Location:
    Galena ohio
    I have a rotor tiller with a briggs 5 h/p engine. It has a updraft carb (mounted to the top of the gas tank) for some reason when I shut it off the carb fills up with gas! I checked and it cakks for a non-vented gas cap. Any ideas?
     
  2. cpd544

    cpd544 Member

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    Check the float, needle, and seat inside the float bowl.
     
  3. Dr.Longshot

    Dr.Longshot Banned Banned

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    5,722
    Like CPD544 said, chec k the float setting, clean the needle and seat, and be sure the cap is venting, hot engine or hot sun can cause pressure in the tank and fllo the Carb.


    Gary Bryant
    Dr.longshot
     
  4. HSLDS

    HSLDS Well-Known Member

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    S-E PA
    Here's a video that might help.

    At about minute 12 he talks about setting the float and needle valve - good video for you, I think
     
  5. 320090T

    320090T Well-Known Member

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    If it is mounted to the gas tank it will not have a bowl, needle, and seat. To have those three items it must have a separate gas tank with a fuel line going to the carb.
     
  6. HSLDS

    HSLDS Well-Known Member

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    320090T is right.

    Just walked to my garage and checked on several leaf blowers... All have B & S engines (5 HP) with the fuel tank directly bolted to the bottom of the carb.

    There is no float bowl... If you pull the tank off of the carb you will see a small brass trumpet that dips down into the tank as a fuel pick up.

    NONE of these has an unvented fuel cap.

    BY the proximity of the fuel tank to the exhaust I suspect you are heating the fuel in the tank, which is effectively sealed save the fuel pick up - as the fuel warms it expands and is forced up the pipe into the carb...

    I'd try a vented cap first...
     
  7. ajhiii07

    ajhiii07 Member

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    Jul 24, 2011
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    all brigs pulse jet carbs use vented gas caps,I'm surprised it runs at any speed above idle
     
  8. halfmile

    halfmile Well-Known Member

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    Location:
    Green Bay Wisconsin
    There is a diaphragm in the carb that brings the gas up by crankcase pulses; that is the movement of the diaphagm works a little pump arrangement with 2 valves, the gas comes up throught the nylon spigot that goes down into the tank. Pull that spigot off and be sure the bottome, (which is like a screen) is not half plugged with depris or paint from the gas tank.

    If there is just a little fuel in the intake when you shut the engine off I wouldn't be too concerned. Without the crankcwase pulses no gas moves.

    HM
     
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