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914UL carburettor gremlins

in 912 / 914 Technical Questions 6 years ago

  • Re: 914UL carburettor gremlins

    by » 6 years ago

    Thank's for all the suggestions!

    The mechanic now has torn down the carb, changed floats and float needle, turned the thing upside down and tested it using pressurised air. It seems to be ok.

    However, after putting it all together again, the engine reverted to what seems similar to my original problems; that is the engine totally losing power and almost cutting off when reaching a certain RPM. In this case just above 3000 as opposed to me getting the power loss somewhere above 4000. Next stop is measuring the fuel pressure and seeing what the fuel pressure regulator is doing...
      
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  • Re: 914UL carburettor gremlins

    by » 6 years ago

    but did you check the float bowl for distortion?
    That what your symptoms indicate.
      
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  • Re: 914UL carburettor gremlins

    by » 6 years ago

    Nope, I hadn’t seen this until after the last teardown. However, I know that both I, the mechanic and the previous owner are aware that there isn’t much force needed for that bottom bolt (I mean, there are really no big mechanical forces at work there) so I doubt that we have ower tightened it. If the leaking continues we’ll check for it for sure.

    The more acute problem now is that the ”original” almost total power loss symptoms have returned. And that shouldn’t really be caused by floats not closing. If anything, more throttle should mitigate the flooding problem, right?
      
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  • Re: 914UL carburettor gremlins

    by » 6 years ago

    I agree with Rob. Number one issue with 914 carbs is over tightening of the plug. You MUST use a torque wrench to properly tighten the plug screw.The float bowl plug torque is 48 in/lbs. Not very much. Over tighten by just a little too much and you have an issue. Plus you may want to try some of the newer rubber bowl gaskets.

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

    Thank you said by: Capt. Siva,
      
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  • Re: 914UL carburettor gremlins

    by » 6 years ago

    The use of a torque wrench is more than essential for this bolts. I m always using it, when I reassemble my carbs and never had problems like power loss. Also I would suggest you to check all the small tubes from the carbs to the airbox for any leak, just to be sure.
    Thank you said by: Capt. Siva,
      
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