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Hi all

In our new plane, the fuel pressure is normally 2.7-2.75 bar in flight. It does not matter if it is the main pump only, or both.
According to the operating manual, it should be 2.8-3.2 bar.

Is this "normal" or is there something I can/should do about it?
It is annoying that the G3X is showing yellow warnings all the time.

Kind regards, Claus
  • Re: Fuel pressure

    by » 8 years ago


    When I was going to make my first flight of my Zenith 750 with the iS, I was alarmed to see the fuel pressure at around 38 psi. My buddy who had been flying the same system in his 750 for a year also had a low fuel pressure (approx 38 psi) without issue, so I decided to fly mine as is. I had no problems. This post prompted me to go look at some in-flight panel photos and low and behold, some recent photos show 42.3 psi. I hadn’t noticed the change. Could it be that my fuel filter is starting to plug up? (Although I recently changed the fuel filter.)

    I am not sure any of this helps, just my experience.

    Cheers,
    Joe

  • Re: Fuel pressure

    by » 8 years ago


    We are having similar problems with a very low hours Rotax 912is Sport

    With the engine stopped, the fuel pressures are within normal ranges (2.9-3.1 bar).

    Once the engine starts, the pressures drop immediately to 2.2-2.5 bar.

    We think it might have something to do with the fuel pressure regulator. If we disconnect the hose between the fuel pressure regulator and the Manifold, the pressures maintain normal ranges, even at idle.

    We have checked all other fuel system components.

    It is very annoying that this sophisticated engine has very little trace for its critical fuel system in the BUDS logs.

    This thread has the looks of a forthcoming service bulletin.

  • Re: Fuel pressure

    by » 8 years ago


    My bet is the fuel pressure sender isn't correct. See if you can attach an in line mechanical gauge to confirm the pressure. Fuel pressure senders across the board for fuel and oil don't don't always have the best rack record.

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


  • Re: Fuel pressure

    by » 8 years ago


    Hi Roger

    Very good input. I forgot that the fuel pressure sensor is not part of the FADEC. I can calibrate it on the Garmin G3X Touch, but I need to find a way to measure it. I do not have this kind on inline pressure sensor.

    Kind regards, Claus

  • Re: Fuel pressure

    by » 8 years ago


    I know I may catch a little flak over this suggestion, but it works out just fine.

    I don't know where you live, but many of us just buy a mechanical gauge and tubing from a hardware store to just confirm a pressure. Cost is usually around $30-$40. It may end up as a one time use item.

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


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