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Went to fly today and fuel pressure was +22 psi before starting - on one or both pumps.  Obviously ran great when I shut down from my last flight.  Have just over 112 hours on the engine.  Engine started ok, but pressure stayed at +22 psi.  Shut down and disconnected fuel supply line to fuel injection rail and flow was excellent.  Disconnected fuel return line from fuel pressure regulator and flow was much lower.  Pressure showed the same +22 psi with the return line disconnected.  Just cleaned corse filter and replaced fine filter around 40 hours ago.  Suspect issue with the regulator.

Before trying to remove the fuel pressure regulator, my ask of the forum is if my symptoms point to a fuel pressure regulator issue to you guys?  I’ve read the section in the Heavy Maintenance Manual about inspection, but hard to believe there’s debris in there with the two filters ahead of it.  Advice and suggestions appreciated. 

  • Re: Low Fuel Pressure

    by » 4 weeks ago


    1. Install mechanical pressure gauge parallel to your electronic pressure sensor and compare the results.

    2. Dismantle the inner part of the pressure regulator and check for some dirt.

    3. Check the pipe between the air box and the pressure regulator for leak. 

    Hope these point will help your finding the problem. 


  • Re: Low Fuel Pressure

    by » 4 weeks ago


    I don't think the engine would run normally at 22 psi, your sender/gauge may have gone haywire.  Can you temporarily swap out your fuel pressure sender to a manual gauge to see if the reading you are getting is accurate?  Or you could adapt a temporary fuel pressure gauge at the fuel rail input. If your connection at the fuel rail is AN-06, there are some great inline adapters that provide a 1/8" NPT port you can screw a standard gauge into.  Check out the Russell 670343, or Summit Racing's SUM-220675 adapter. 

     

     

     

     


  • Re: Low Fuel Pressure

    by » 4 weeks ago


    Just as a data point, had a friend lose pressure in flight down to 23 psi. He said the engine ran fine but of course he landed at the nearest field. We ended up putting in a new 2021 fuel pump assembly to replace the 2020 that was in there.


  • Re: Low Fuel Pressure

    by » 4 weeks ago


    Never mind…. Just got back from the hangar.  To make a very long story short, on Saturday I loaded a totally unrelated firmware patch from Dynon.  Unbelievably, it RECONFIGURED my fuel pressure to the non differential 75 psi sensor!!!???  Changed a couple of other things too.  Lesson learned!  Thanks for the suggestions though. Good information for the next time!


    Thank you said by: Bill Hertzel, RotaxOwner Admin

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