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Briggs will only start, and run for a moment, if I manually close the carb butterfly

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TheScutFarkisAffair
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2019/11/03 10:26:58 (permalink)
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Briggs will only start, and run for a moment, if I manually close the carb butterfly

Toro push-mower with a Briggs 2H802/1767-E1.I've disassembled the carb and cleaned it, and check the float and needle. It's getting fuel and all the jets are clean and working. If I dissconnect the governor spring and manually close the butterfly valve, it will start a run for a second. If I reattach the spring (which leaves the butterfly open), it won't start at all. Any ideas? Here is a pic of the carb linkages. Is it missing anything? Maybe a spring?  Should the butterfly be closed at starting?
post edited by TheScutFarkisAffair - 2019/11/03 10:41:57

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    AVB
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    Re: Briggs will only start, and run for a moment, if I manually close the carb butterfly 2019/11/03 11:20:29 (permalink)
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    Briggs 12H802-1767-E1.
     
    Two things to double check.
    1. Fuel bowl retaining bolt/main jet is clean. The main jet is in the center of this bolt that goes down to a cross hole.
    2. Since this a primer type carburetor, that primer is actually priming the carburetor. The air filter/primer are bad to warp leading to non-priming. Requires either a new air filter base or two gasket glued together and beveled to ensure sealing of the primer air pulse passage.
    TheScutFarkisAffair
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    Re: Briggs will only start, and run for a moment, if I manually close the carb butterfly 2019/11/03 11:39:07 (permalink)
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    I took apart the carb and cleaned all the jets and needle and ensured they were clean and open; they are.  Are you saying that it won't run properly without the air cleaner and priming bulb attached?  It has a new air cleaner to carb gasket and it's not warped.
     
    As I said, it does start, it just won't stay running, and it will only start if the butterfly is manually closed.  I feel like it should be closed via a spring, and then governor opens it up when running, but I can't figure out if that's correct or not.  The parts listings I can find don't show an assembled unit.
    post edited by TheScutFarkisAffair - 2019/11/03 11:45:33
    AVB
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    Re: Briggs will only start, and run for a moment, if I manually close the carb butterfly 2019/11/03 11:58:32 (permalink)
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    It is right the opposite on governor operations. The spring holds the throttle vane side open when not running and the governor will work against spring tension to close the throttle vane to slow the engine when the engine is running. Governor are meant to slow the engine. It is the delicate balance between this governor closing action and the spring wanting to open the throttle fully. Without the spring the engine will never do anything other than idle.
     
    It just will not prime the carburetor without it in place as priming takes the place of choking the engine.
     
    As the new air cleaner gasket take off the cleaner and look at the impression of the air cleaner makes on the gasket. It should be uniform. And don't over tighten the mounting screws as this will warp the air filter base.
    TheScutFarkisAffair
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    Re: Briggs will only start, and run for a moment, if I manually close the carb butterfly 2019/11/03 12:02:43 (permalink)
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    Air cleaner looks fine.  I just realized that my other push mower has the same engine, so I compared it against it, and everything seems to be in order.  Funnily, it won't start either, despite starting perfectly all summer.  Riding mower starts and runs fine.
     
    It's cold here now (in the 40s F).  Would that affect it?
    TheScutFarkisAffair
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    Re: Briggs will only start, and run for a moment, if I manually close the carb butterfly 2019/11/03 12:56:32 (permalink)
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    Update:
     
    I went to the auto parts store to get some more carb cleaner and went ahead and bought some starting fluid spray.  A quick spray in the carb and it started just fine.  I guess the primer bulb is cold and stiff and the mower was just too cold.
     
    Runs fine!
    Roy
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    Re: Briggs will only start, and run for a moment, if I manually close the carb butterfly 2019/11/03 14:44:05 (permalink)
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    Do the engine a favor and leave the ether on the shelf. It washes the lubricant off the cylinder walls, you should see what it does to aluminum bore engines.
    TheScutFarkisAffair
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    Re: Briggs will only start, and run for a moment, if I manually close the carb butterfly 2019/11/03 14:52:08 (permalink)
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    Interesting...just looked it up!

    Would it be safe to shoot a squirt of carb cleaner in there instead?
    Roy
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    Re: Briggs will only start, and run for a moment, if I manually close the carb butterfly 2019/11/03 18:31:44 (permalink)
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    Carb cleaner, WD-40, gas, anything but ether.
    Trmt701
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    Re: Briggs will only start, and run for a moment, if I manually close the carb butterfly 2019/11/05 15:54:37 (permalink)
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    This I did not know Roy. Thank you. No starting fuel. Real fuel. Thanks!!
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