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While flying, almost an hour at 4500', a fuel pressure warning comes on. I switch to the engine screen, on the G3X, and see the pressure at 7.2 psi.  I reduce the rpm from 5450 to 4900 and the pressure reduces to 6.7 psi.  I have another hour before landing at the home airport. The pressure fluctuates between 5.6 and 8.0.  Fuel flow shows no issues. Gas consumption is normal and  rpm holds steady.  I have 300 hours on this fuel pump without incident. Anytime I increase the rpm above 5050 the pressure hits the max limit.  At no time did the fuel pressure exceed he maximum for longer than 15 seconds.  What is this an indication of? 

  • Re: High fuel pressure

    by » one month ago


    You may have a fuel pressure sensor going bad, especially if its mounted in a way that it picks up engine vibration. Both the oil fuel pressure and oil pressure sending units seem to have shorter livers when subjected to engine heat and vibration. These should be remote mounted on the firewall to isolate them. Here is a link to the fuel pump diagram and theory of operation provided by Rainbow Aviation it indicates how the pressure is set by spring pressure. 

    https://electricmotorglider.com/2018/09/21/fuel_pump_912/


  • Re: High fuel pressure

    by » one month ago


    Thank you for your input.  I just spoke to Steve, at Aircraft Specialty, and learned his father flew yesterday morning and experienced the same thing.  They thing this may be a result of seasonal fuel changes.  I will run this tank out and refill to see if things improve.  This plane has been flying flawlessly for over 250 hours.  


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