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Thread: Fuel flow readings 25% to high

  1. #1

    Fuel flow readings 25% to high

    I have a non-s-3500 and a 3400 in my Glastar Sportsman built by PCA and the panel worked fine for 50 hours. Lately when refueling I realized that I could put in only 80 liters although the EFIS stated that I had used 100 liters. The fuel flow reading in level flight at 75% power LOP are also higher than before and therefore adding up more fuel used.

    Is there an easy way to change some parameters in the EFIS to correct this mis-reading in a simple way?

    The fuel flow transducer used on my Lyc IO390 engine is of the the type: "little red little box" - sorry, but I do not recall the exact type and the plane)


  2. #2
    Sure, we have a formula to set the correct K-factor for Fuel-Flow. Please see the user manual for that information, under the Fuel-Flow section.

    "The accuracy of the fuel computer is affected by the value of Counts per .01 gals (K Factor). The Counts per .01 gals
    (K Factor) sets the calibration of the instrument to match the flow transducer and the variations in the installation. After
    running a tank of fuel use the following formula to adjust the accuracy.

    The Counts per .01 gals (K Factor) is adjusted from the Fuel Flow/Computer page in Instrument Calibration.
    New Counts per .01 gals = (Old Counts per .01 gals) x (Disp GAL USED/PUMP GALS)"
    Trevor Conroy
    Technical Support
    Advanced Flight Systems

  3. #3
    Join Date
    Mar 2010
    Fredrikstad, Norway

    I had the same problem...

    ... and is this tread, the problem was solved thanks to Trevor.

    It turns out the K-factor is different for US GLS and litres.

    270 hrs per Sept 2013 on my first RV-7; "Wilco"
    Now final assembly on my second -7; "Kermit"
    3500 EFIS in Wilco.
    4500s and 3400s in Kermit.
    Great products and customer support from AFS!

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