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Cleaning Out Contaminated Fuel

in General Tech Discussion 8 years ago

  • Re: Cleaning Out Contaminated Fuel

    by » 8 years ago

    High DA should not cause an engine to all of a sudden drop 25% power. We have a Page, AZ fly-in coming in Oct. where it is almost all lSA and we fly out of 7500-9500 DA fields and not a single person has had an issue for 8 years and 30 planes every year. many LSA 912 operated engine fly out of these altitudes all the time and no one has an issue. Something else here is going on.

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

      
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  • Re: Cleaning Out Contaminated Fuel

    by » 8 years ago

    The problem seems to be solved after I did the following things:
    - Cleaned the air filters (the desert and alkali lake where I had landed were quite dusty; filters were somewhat dirty).
    - Disassembled all fuel lines firewall to carbs and made sure they were free (found nothing).
    - Replaced fuel filter.
    - Did fuel flow test (good).
    - Checked GA prop pitch to make sure it had not changed (no change).
    - Removed and checked all spark plugs (all looked good).
    - Checked exhaust system for obstructions (all good).
    - Checked carb boots and sync (all good).
    - Checked throttle cables & travel & choke cables release (all good).
    - Removed carb float bowls and checked floats (all clean & good).
    - Checked ignition plugs & grounds (all good).
    - Took large fuel sample (appeared correct color, no dirt or water, smelled OK).

    I then went for a test flight, with the same fuel, and all seemed to be back to normal. I now believe the problem wasn't bad fuel, but a combination of things such as: dirty air filters, hi altitude, increasing temperature thru the day, plane loaded near gross with CG near the rear of the envelope, and my inexperience with hi DA at these conditions. It is also possible that my thorough checkout of the fuel system could have dislodged some partial blockage that I did not notice. All appears to be good now; thanks for the helpful comments.
      
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  • Re: Cleaning Out Contaminated Fuel

    by » 8 years ago

    FYI, something I learned during my fuel flow test recently: disconnecting the fuel line right at the carb gave just a trickle of fuel from my high wing wing tanks. I thought maybe I had found the problem, but then I put a jumper hose around the Rotax mechanical fuel pump and the flow at the carbs increased drastically. I had heard that the Rotax fuel pump (mine is the newer model) is somewhat of a restriction when it is not rotating, but did not realize it was this drastic. Any fuel flow testing that goes thru that pump will not be even close to representative of the rest of the fuel system. Probably you all already know this, but thought it worth mentioning.
      
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