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B&S 5hp engine suddenly runs slower?

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handypfb
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2019/11/05 10:14:08 (permalink)
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B&S 5hp engine suddenly runs slower?

My Craftsman Leaf Shredder powered by a B&S 5hp engine (model133412) runs great for 30-40 min then suddenly slows to close to idle. NOTE: I have to keep moving the CHOKE lever to keep the engine running. I removed the CLEAN air filter (NO change), and the gas cap. Later I removed the carb fuel bowl. It was clean. The next day started and ran great for about another 30 min, then as before it slowed to close to IDLE (not changing the throttle position).

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    Roy
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    Re: B&S 5hp engine suddenly runs slower? 2019/11/05 11:30:51 (permalink)
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    Can you post the engine numbers, not the ones from the emissions sticker, so we can tell what you are looking at? If the choke makes a difference the carb is partially plugged. Does it have a fuel filter?
    handypfb
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    Re: B&S 5hp engine suddenly runs slower? 2019/11/05 13:22:10 (permalink)
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    I have a B&S  "INDUSTRIAL PLUS" 5hp (circa 1994 I think).
    Besides Model #133412 are:  Type 005901  and Code 94102707
    It is the engine for a Sears Leaf Shredder 
    Model#247.795950   Serial #1A095A10056
    FUEL FILTER?
    If there is one it is not readily visible. There was NOT one in the Carb fuel bowl and the 1/2" VENTED nut that secures the bowl was clear and clean.
    AVB
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    Re: B&S 5hp engine suddenly runs slower? 2019/11/05 15:25:27 (permalink)
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    That is actually the main jet assembly. Try loosening the fuel cap.
    Roy
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    Re: B&S 5hp engine suddenly runs slower? 2019/11/05 15:29:11 (permalink)
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    Check the fuel line near the tank, the parts list indicates an in line filter. It may be partially plugged
    handypfb
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    Re: B&S 5hp engine suddenly runs slower? 2019/11/06 11:19:38 (permalink)
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    Thanks for your reply.
    I actually removed the gas cap when it FIRST happened.
    I have studied the gas/carb diagrams (parts list). Where it shows a Fuel Filter (part #240), it does NOT  look anything like my engine. Mine is a plastic shut-off valve. ON/OFF. I disconnected the line and actually removed the gas tank.
    Gas flowed freely and it was clean. YES. it could be an intermittent disruption of gas flow lasting several minutes at idle speed, but the next day (with no changes/fixes,etc.) it ran normal as I said for over 30 minutes.
    NOTE: My on-off valve does not look like it could also be a filter, and it doesn't look like the filter pictured in the parts diagram (#240  $3.04 or $3.80). 
    Note #2
    When I removed the gas tank and the metal housing it exposed the top of the Carb and the rest of the fuel line to the Carb (no fuel filter seen).
    What I did see was TWO linkages that go to a "flange" on the top of the Carb. One is a solid piece and the other a VERY THIN (with a spring about 3/4" long) SURROUNDS this linkage. Where both ends of the solid heavy linkage are attached, the VERY THIN linkage is not attached to a very small hole in the carb flange. It has a slightly bent curve at the end and it just might have become FREE from it's designated hole right next to the solid linkage which is attached to the carb flange.
    Whew!
    Roy
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    Re: B&S 5hp engine suddenly runs slower? 2019/11/06 11:35:45 (permalink)
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    That spring is not critical in your application, it keeps the rod from slopping in the hole as it wears. It sounds like the carb needs a thorough cleaning, a small passage is partially plugged.
    handypfb
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    Re: B&S 5hp engine suddenly runs slower? 2019/11/06 11:56:10 (permalink)
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    Thanks again for your help.
    I will try again today and if it repeats I will overhaul the Carb.
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