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Craftsmen 16 hp. Model 310707. 42 inch cut.

Ohler
10 years ago

OK. I have checked the carb three times now all is clear. I have reset the valves. The tractor starts and runs for a few minutes. I am at a lose. The carb will shut off the fuel not running. No leaks, tank level is consistent. When I start the tractor it will consume a lot of fuel, to the point it floods out.
Any Ideas???

Comments (20)

  • bill_kapaun
    10 years ago

    Is the Main Jet installed?
    Choke OFF?

  • rustyj14
    10 years ago

    The carburetor float may have a leak in it.
    Rustyj.

  • Ohler
    Original Author
    10 years ago

    Yes , jet installed. Fuel is electrically controlled with solenoid. Nikki carb.
    Float is working.

  • Ohler
    Original Author
    10 years ago

    It doesn't make it to choke. Runs at idle and starts flooding from there..

  • bill_kapaun
    10 years ago

    "Fuel is electrically controlled with solenoid"

    The solenoid is NOT a fuel shut off!!!
    It simply blocks the Carb MAIN JET to prevent after fire.

    It is no way connected to the float/needle/seat.

  • Ohler
    Original Author
    10 years ago

    I know that Bill, I'm just trying to get some idea's as to why my carb is drinking so much fuel. I can start it at low idle and it runs ok. Choke is midway up the handle. It never makes it that far up the handle to choke position, before it starts pouring out black smoke. It sucked down a quart of gas in about five minutes...

  • bill_kapaun
    10 years ago

    Post the sears 917.xxxxxx number.

    I surmise you have an engine with a fuel pump and your carb needle & seat IS leaking through. Just not when the engine is off.

  • Ohler
    Original Author
    10 years ago

    No fuel pump, gravity fed. The jet is pulling way to much fuel. I shut off the idle mixture and it still runs, to much fuel. Guess I'll just break down and purchase a new carb. Or , do you know if the valve adjustment has anything to do with it pulling to much fuel?

  • rcbe
    10 years ago

    Have you cleaned/changed the engine air filter lately? And do your carb throttle/choke butterfly plates seem to respond properly to the dash control knob movement?(chk by looking directly down into carb throat while moving throttle control thru full range with engine OFF)....

  • Ohler
    Original Author
    10 years ago

    New air filter. Everything is working properly. Looking in the carb you can see that the fuel is coming out to fast. When the tractor is on, not running, solenoid open. There isn't any fuel leaking, ie coming out of the jets. I work on cars and such, from old to new. Rebuilt plenty of rochesters. This one is way to simple. Thing is I haven't worked on to many lawn tractors. Engine set up that is. Some thing with the engine that could cause this. Or do I need a carb?

  • mownie
    10 years ago

    OK, so far as you can tell, there is no fuel issuing from the carb into the intake plenum when the engine is not running?
    If this is true, the float, needle & seat are most likely operating correctly.
    Be aware that the carburetor does not force fuel into the engine. The engine induction system creates a negative pressure (aka venturi vacuum) that allows fuel to flow out of the carb bowl only when this venturi vacuum is present (engine running). In essence, the fuel is pushed out of the bowl by atmospheric pressure pressing down on it. IF.......there was a problem with the float, the needle valve, or the needle valve seat..........the engine would be getting drowned with fuel whenever the tractor was stored, even overnight.
    So, let's think what might allow too much fuel to flow out of the carb when the engine is running.
    I can only think of only a few things that might cause this to happen.
    1. Pilot jet completely absent. This would allow fuel to flow in a much greater volume than the constricting pilot jet ever could.
    2. Main jet is not seated properly into its bore, or is missing its gasket or o-ring, or the main jet is "cross threaded" in pace and even though it feels tight, it is not sealing and thus fuel is bypassing the restricting orifice of the jet, and so the fuel is not actually metered by the main jet.
    3. Float level is set too high, but not high enough to cause fuel leakage past the needle when engine is off.
    This would be a very fine tightrope to walk, in that a little too high can cause an overly rich mixture, while just a little higher and you would begin to see fuel drowning the engine in storage.

    Valve adjustment will not affect excessive fuel flow.

    You state that you have checked the carb 3 times. Have you disassembled the carb at some point in your endeavors?

  • Ohler
    Original Author
    10 years ago

    Every time. It's a simple carb. I made absolutely sure every passage was clear.use this link to see it. Nikki carb.
    http://www.briggsandstratton.com/us/en/support/manuals/results?NTT=310707-0136-E1

  • mownie
    10 years ago

    Replace the carburetor.

  • Ohler
    Original Author
    10 years ago

    Didn't really want to hear that, but thanks. Any specific reason?

  • bill_kapaun
    10 years ago

    Because you've convinced yourself you've fixed your current carb and it still doesn't function properly?

  • mownie
    10 years ago

    The fuel tube plate with 2 screws to hold it down, and the labyrinth O-ring seal, seem to be problematic about keeping everything in control and sealed off from leakage.
    I think these fragile plates are prone to warpage and that is probably why the excess fuel delivery.

  • Ohler
    Original Author
    10 years ago

    Bill, I am an innovator.. I fix things that can't be fixed.. Convincing me is a very big problem. I make things work Properly, that has no reason behind what I do. Genius, NO. Imagination, yes. Smart yes. I fixed my tractor. Runs great. Took a little time, Once I had some Info. That is the great things about these sites. INFO. What I did I will tell in time

  • Ohler
    Original Author
    10 years ago

    Thanks Mownie. With your info and others, I have come to see how these work. I have fixed my problem. If this fixes problems with Nikki carbs I will post in the near future. As I wont post with non proven advice. Thanks again. Ps, Thank you also Bill.

  • bill_kapaun
    10 years ago

    Since these forums are to share information, would you "share" what your $.20 fix was?

  • Ohler
    Original Author
    10 years ago

    Soon Bill. I have to make sure it stays in place. Or have to redesign it. Thanks again..Let you know soon.

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