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 Rotax 912 ULS installed in RV 12 

2018 Built

180 Hrs no Issue before

Fuel PSI showing high for most of the time. it used to show low PSI during take off for a minute or less, Now its showing high and goes red with big X sign most of the time.

it happens in most of the time in flight altitude 4000 feet, Over 4000 RPM

What I did ?

- I took off sensor and hook up PSI gauge to make sure my engine driven pump and electric pump are working. (4PSI)

Both works fine. It has electric fuel pump on all the time. 

-it s so weird  it shows hig PSI only when I use 100LL gas, When I use auto gas it seems fine !! UNBELIEVABLE 

Anyone else having similar Issue ? 

Experts input are well come.

  • Re: 912 ULS Fuel PSI

    by » 9 months ago


    Your Mechanical Gauge is showing 4 psi.
    What pressure is the panel gauge showing when you say it is "High". How High? What number?

    Gauge Pressure is measured relative to the ambient pressure. 
    The ambient pressure drops about 1" hg per 1000 feet of altitude or ~0.5 psi/1000ft.
    So, you might expect to see an apparent 2 psi pressure increase at 4000 ft. 
    Actually, less as the pump will be non-linear, but a 1 to 1.5 psi apparent increase might be expected.

    The fuel pressure Red Line is 0.5 bar (~7psi).
    What is your alarm point set at?


    Bill Hertzel
    Rotax 912is
    North Ridgeville, OH, USA
    Bill.Hertzel@Yahoo.com
    Clicking the "Thank You" is Always Appreciated.


    Thank you said by: Pramod Regmi

  • Re: 912 ULS Fuel PSI

    by » 9 months ago


    Do you have a Dynon? It is my understanding that the big red X on the Dynon does not (necessarily) indicate that you have exceeded the fuel pressure limit for the engine, but rather that you have exceeded the fuel pressure limit for the sensor. If this is Dynon, make sure that you have the correct sensor selected in your configuration.

     


  • Re: 912 ULS Fuel PSI

    by » 9 months ago


    Psi is more than 7 is high, after 12 it goes out with big red X,

    2 to 5 PSI is normal in dynon HDX I got.

    Its got kavlico sensor with 3 wire system. dynon sold it in $139.

    Everything is configured right. It was working fine all this years.

     

    What question ya ll git ??? 


  • Re: 912 ULS Fuel PSI

    by » 9 months ago


    I tend to agree with the others.
    The Red X is indicating a Sensor out of range or wiring failure.
    The fuel pumps are not physically capable of producing 7psi.
    And your mechanical gauge shows you are really at 4 psi.
    I would suspect a wiring problem before a sender problem.
    Wiring is often intermittent, senders tend to only fail once.
    Higher sensor output voltage displays as higher pressure.
    If you are losing the ground to the circuit, the output signal will tend to float upwards.


    Bill Hertzel
    Rotax 912is
    North Ridgeville, OH, USA
    Bill.Hertzel@Yahoo.com
    Clicking the "Thank You" is Always Appreciated.


    Thank you said by: RotaxOwner Admin

  • Re: 912 ULS Fuel PSI

    by » 8 months ago


    330UF  25V Small Capacitor took care of the Issue.

    Aluminum Electrolytic Capacitors - Radial Leaded Aluminum Electrolytic Capacitors - Radial Leaded 330UF 25V

    Where Do I get this Idea from ?????

    John the genius.....

    Dog Aviation........

    Thanks a lot John....


    Thank you said by: Wayne Fowler

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