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  1. #1

    Join Date
    Apr 2012
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    MTD - Yard-Man

    18.5hp B&S mower flooding and will only run while choked

    B&S Engine Model 42A707 1653-01

    Hello all, I can't get this thing to run off choke.

    I replaced the fuel lines, fuel filter, fuel and spark plugs. I checked compression at 120 psi in both cylinders. Spark was checked with a plug at 0.060" gap to check power of spark and both cylinders sparked fine. I re-gapped at 0.030.

    I rebuilt the carb, blew out all passages with carb cleaner/compressed air. I am on round 3 of tearing this down and blowing out each port.

    While it is running while choked, dropplets of fuel are spraying out of the carb throat onto me and everything else in the area. When I shut it down, I can see fuel puddled at the collector below the carb. Plugs aren't wet.

    Any suggestions? Thanks

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  3. #2

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    kioti/rhino finish mower

    Re: 18.5hp B&S mower flooding and will only run while choked

    Sounds like there is still a jet plugged up in the carb someplace that you haven't found yet. that carb on the opposed twin is bad at spitting fuel back out of the carb. Have seen several that pool the fuel in the bottom of the intake manifold.
    ILLINOIS ENGINE, BEECHER CITY, IL
    BRIGGS AND STRATTON MST (MASTER SERVICE TECHNICIAN)
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  4. #3

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    MTD - Yard-Man

    Re: 18.5hp B&S mower flooding and will only run while choked

    I'll tear it down again.

    Should I removed the welsh plug? What is the easiest way to remove this if necessary? I also couldn't find any specs on the float setting.

    Thanks for the help.

  5. #4

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    Re: 18.5hp B&S mower flooding and will only run while choked

    A sharpened punch works decent to remove the welch plugs. Just make sure you can get a new one before removing. On some of the Briggs carbs the only way to get the plug is in the carb kit. Briggs floats sit level in the carb, providing the needle valve doesn't have the antibounce feature.
    ILLINOIS ENGINE, BEECHER CITY, IL
    BRIGGS AND STRATTON MST (MASTER SERVICE TECHNICIAN)
    Sales and Service for Dolmar, Poulan, Briggs and Stratton, Kohler, Lauson(Tecumseh, LCT), Generac, Brute.
    Warranty service for MTD, Murray, Powerwasher, Karcher, Mcculloch, Earthwise, Earthquake, Yamaha engines, Sanborn(powermate, Kobalt), Southland, Hisun, American Sportsworks, Worx, Rockwell Tools, Great Lakes Technologies products(Wen, CZ), Efco, Snap-On pressure washers, and others.

  6. #5

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    MTD - Yard-Man

    Re: 18.5hp B&S mower flooding and will only run while choked

    The needle just has the spring clip that connects to the float - that's not the anti-bounce you're referring too, right?

    With the welch plug, do I just strike an edge with the punch so the plug will rotate to be plucked out with needle nosed pliers?

  7. #6

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    Re: 18.5hp B&S mower flooding and will only run while choked

    The anti bounce is built into the needle valve itself so I would say you don't have the anti bounce. You will need to punch a hole through the plug at an angle to avoid damaging the transition ports underneath, and then pry it out.
    ILLINOIS ENGINE, BEECHER CITY, IL
    BRIGGS AND STRATTON MST (MASTER SERVICE TECHNICIAN)
    Sales and Service for Dolmar, Poulan, Briggs and Stratton, Kohler, Lauson(Tecumseh, LCT), Generac, Brute.
    Warranty service for MTD, Murray, Powerwasher, Karcher, Mcculloch, Earthwise, Earthquake, Yamaha engines, Sanborn(powermate, Kobalt), Southland, Hisun, American Sportsworks, Worx, Rockwell Tools, Great Lakes Technologies products(Wen, CZ), Efco, Snap-On pressure washers, and others.

  8. #7

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    MTD - Yard-Man

    Re: 18.5hp B&S mower flooding and will only run while choked

    Not a single change... It will only idle with the choke closed 80-100%. I've got to jog the choke to keep it running.

    I swabbed each port/jet with a piece of appropriated sized copper wire. Set the float level, pulled the welch plug...

    I am at a loss.

  9. #8

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    Ariens

    Look for air leak?

  10. #9

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    Toro

    Re: 18.5hp B&S mower flooding and will only run while choked

    Had the same problem about 5 years ago and found an air leak between the manifold and the block.

  11. #10
    SONOFADOCKER's Avatar
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    TORO,JACOBSEN,CRAFTSMAN

    Air leak is possible . Look for loose manifold bolts or a hair line crack . I had a carb suck air around the idle gas adjustment needle .

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