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I have a drip of fuel  back thru the air-filter on one of my carburettors if the fuel is not turned off after shut down. This started about 20 hours ago ( the engine has around 800hours)

 

I have recently done an overhaul on both carburettors with no change. I am somewhat puzzled and would appreciate suggestions on what to check or look for

Ian

  • Re: Leaking carburettor 912

    by » 2 days ago


    What's the fuel level like in the float bowl? If the float valve isn't shutting off then the fuel level will rise until it fills the bowl, goes through the jets and runs out into the air filter. Are the floats sinking or is there a problem with the float valve tip or seat?


  • Re: Leaking carburettor 912

    by » 2 days ago


    I will review the float levels and check the floats, being new I don't think they should be a problem. The needle is new and the seat did not look worn. Thanks for your reply.

     

     


  • Re: Leaking carburettor 912

    by » 2 days ago


    What weight were (are) the floats?

    Did you overhaul the carbs yourself?


  • Re: Leaking carburettor 912

    by » Yesterday


    Hi Ian,

    I went through these exact symptoms 6 months ago. I bought a plane with 60 hours on it. I had it hangared for a few months while I finished my training. When I was ready to use it for my tailwheel endorsement, it would drip from the air filters. Sometimes both. Sometimes only one. So I had the carbs overhauled by a certified Rotax guy. No change in symptoms. So then we noticed every time we dropped the bowls to inspect there was a very fine debris in the bottom. Thinking it was fuel contamination, we flushed the tanks until clear. Not finding anything there, we worked forward with each component looking for issues. It was when we finally got all the way to the mechanical fuel pump that we found significant debris flushing from it. So we removed it and disassembled it and found it rusting inside. Presumably from sitting up with water in it. Months prior I had found significant water accumulation in my tanks. I was hangar hopping around the airport until I had my own hangar and it being a Highlander, I was keeping my wings folder so I could shack up with whoever could accommodate me. Haha. Couldn’t keep the tanks full with folded wings. So after installing a new fuel pump, zero fuel issues. Good luck finding your issue. By the way, we were using an open white container to sample fuel. That helped us see the contamination. 


    Wade

    29774_2_00094475-C49F-4719-9C82-C3B7D357A488.jpeg (You do not have access to download this file.)

    Thank you said by: Wayne Fowler

  • Re: Leaking carburettor 912

    by » Yesterday


    My guess is either the floats in that carb are heavy or the brass float armature height isn't properly set which allows the fuel level to be too high and drip out of the carb. It is also possible, but NOT highly probable it could be a bit of debris in the needle valve seat.

    Out of curiosity is this a tail dragger? 


    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell


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