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Third fuel pump on 912 iS engine installations

in 912iS Technical Questions 7 years ago

  • Re: Third fuel pump on 912 iS engine installations

    by » 7 years ago

    I have a Flight Design CTLSi (912iS engine) here in Tucson, AZ. Last summer's temps were 110F- 115F and this aircraft had no issues. A third pump to recirculate fuel for vaporization on a hot day should not be needed. The 912iS engine recirculates a huge amount of the fuel pumped compared to the 912ULS. So long as the fuel goes back to a cooler header tank heat shouldn't be the issue. Cool fuel should be recirculating like crazy in the 912iS engine.

    Rob,
    Refresh my memory (I forgot) on the amount (%) of fuel recirculated in the 912iS engine. I thought it was like 60%-70%?

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

    Thank you said by: james porter
      
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  • Re: Third fuel pump on 912 iS engine installations

    by » 7 years ago

    Thanks for the info.
    Are you using auto fuel with those temperatures?

    Do you do refueling and multiple flights in those temperatures? (with auto fuel)
      
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  • Re: Third fuel pump on 912 iS engine installations

    by » 7 years ago

    Can I just ask what filters you're using, James. Again, I have no personal experience of any of these problems, nor solutions, but I was reading another article this morning in the latest copy of the same magazine and in it a few lines discussed some fuel pressure problems with a 912iS when a different filter to the Rotax equipment (Bosch) was used. It was also questioning the placement of the fuel pressure sensor but I did think of your situation and if you're using any filter other than Bosch it might be worth swapping them out and seeing if that cures your problem.
    Thank you said by: james porter
      
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  • Re: Third fuel pump on 912 iS engine installations

    by » 7 years ago

    Thank you for the suggestion.
    As mentioned in my post, I use the Rotax fine fuel filter.
    The fuel filter would probably only affect fuel pressure. Generally causing an increased pressure in the case of obstruction. Fuel under high pressure is very resistant to vaporization. It takes much higher temperatures to vaporize the fuel at 42 to 44 psi.
    In my instance the fuel is vaporizing in the low pressure side of the fuel system at the inlet of the fuel pump(s).
      
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  • Re: Third fuel pump on 912 iS engine installations

    by » 7 years ago

    It can be 100F+ here from May - Sept.

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

    Thank you said by: james porter
      
    Report
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