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I noticed that the Electrical Fuel pump that was installed 2 years ago during the annual on my Pipersport only provided 0.1-0.2 PSI when turned on. The Pump was Facet Model 40178 which was rated at  2.0-3.5 PSI.

After reading some threads in this forum I noticed that the recommended fuel pump is the Facet Model 40105. Thus, we replaced the above mentioned with this model.

Upon replacement, I turned the new pump on and noticed that the fuel flow moved up to about 1.5 GPH while the pressure went from 0 to 0.2. This seemed odd. We then proceeded to check if there was any fuel pumped by disconnecting the out put hose. When turned back on, the pump did show fuel being pumped.

With that, the hose was re-installed and the fuel pump was re-started. This time, the fuel flow went a bit higher temporarily while the fuel pressure indicated went up slowly to 1.8 PSI. This is the behavior I expected but I am not sure if the pressure reading is correct.

Later the aircraft was returned to the hangar and turned off. The fuel pump was again turned on to see if there would be a pressure build up. However, to my surprise, the pressure never went above 0.2 PSI again.

Does anybody have a similar experience? Would appreciate any inputs.

  • Re: PiperSport Electrical Fuel Pump

    by » one month ago


    I do not have specific knowledge of Facet pumps only general understanding of how pumps work.

    The following questions/observations may assist someone else to give a more "targeted" answear:

    Facet type pumps are, I believe, positive displacement - that is for every stroke a fixed quantity of liquid is moved. 

    The pulsing sound you here when the pump is switched on, is the sound of the "piston" moving.

    The pump will turn off when it senses a prefixed pressure has been reached.

    Most pumps will read the lowest pressure when there is no/minimal restriction to flow ie as restriction is applied so pressure will rise.

    In the context of a fuel supply to the engine, pressure is not as important as flow/volume. As long as there is sufficient pressure to overcome valve springs, gravity and push out vapour, it is usually sufficient. It is however an indicator of fuel delivery system "health"

    So;

    Has the pump been correctly installed? Fuel flow direction is usually indicated on the pump by a directional arrow. Two wires + & - make sure they are correctly attached.

    When you turn your pump on: Is the pulsing sound rapid? Followed by a slowing? Finally coming to a near (occasional pulse) or complete stop (nil fuel flow)?

    Does your fuel system have an excess fuel bleed/return to tank? If so, is it a fixed or adjustable return?

    Are there any fuel leaks? Check mechanical pump, all hose connections and carburettor float bowl.

    Are tank to pump hoses/lines are all in good condition? Kinked/pinched lines. Check for air tight connections. An air bleed will impact on the pumps ability to deliver both pressure & volume.

    If your fuel pressure gauge/sensor is working correctly it should start with a nil reading, followed by a steep rise, ending in a constant reading,    that will only change when there is a fuel flow (engine start/fuel consumption). Is this what you see?

    Is there a fuel filter on the supply? delivery? side of the pump. If so is it clean? What sort of filter?

    Is the engine delivering its expected power? If so, this would suggest sufficient fuel is being delivered to the carburettor float bowls and the system is working satisfactorily (possible faulty gauges/sensors).

    I cant think of anything else at the moment.

    Good luck.

     

     

     

     


  • Re: PiperSport Electrical Fuel Pump

    by » one month ago


    Sean,

    Thank you very much for taking the time to provide this valuable information. I will respond to your questions below.

    1. Has the pump been correctly installed? Fuel flow direction is usually indicated on the pump by a directional arrow. Two wires + & - make sure they are correctly attached. -----> JC:  Yes, this is correctly installed.

    2. When you turn your pump on: Is the pulsing sound rapid? Followed by a slowing? Finally coming to a near (occasional pulse) or complete stop (nil fuel flow)? ----> JC: It starts fast and then slows down as the pressure builds

    3. Does your fuel system have an excess fuel bleed/return to tank? If so, is it a fixed or adjustable return? ---> JC: Yes it does have a return line to the tank. I do not know if it is fixed or adjustable. Will investigate.

    4. Are there any fuel leaks? Check mechanical pump, all hose connections and carburettor float bowl? ----> JC: I suspect there may be based on what I have observed and what you are stating.

    5. Are tank to pump hoses/lines are all in good condition? Kinked/pinched lines. Check for air tight connections. An air bleed will impact on the pumps ability to deliver both pressure & volume. ---> JC: They appear to be good. However, I will check them once again.

    6. If your fuel pressure gauge/sensor is working correctly it should start with a nil reading, followed by a steep rise, ending in a constant reading,    that will only change when there is a fuel flow (engine start/fuel consumption). Is this what you see? ---> JC: I saw that once. However, when I tried the other two times, the pressure reading was stuck at 0.2PSI. The fuel flow went up and then down to zero.

    7. Is there a fuel filter on the supply? delivery? side of the pump. If so is it clean? What sort of filter? --> JC: No, this was checked vs. the Maintenance Manual diagrams. Filters are at the output of the fuel tanks, not at intake of the electrical pump.

    8. Is the engine delivering its expected power? If so, this would suggest sufficient fuel is being delivered to the carburettor float bowls and the system is working satisfactorily (possible faulty gauges/sensors). ---> JC: So far, even when I have gotten low fuel pressure warnings while in flight, the fuel flow has remained steady and the engine behavior has been normal. No loss of power, nothing.

    My next step is to measure the pressure on the system with an external gauge. This will reveal if there are any leaks and if the pressure sensor is not working properly.

    Once again, thank you for your valuable information.

    JC


    Thank you said by: RotaxOwner Admin

  • Re: PiperSport Electrical Fuel Pump

    by » 6 weeks ago


    Update:

    Upon further analysis, it was found that the pressure sensor was not configured correctly on the Dynon D120. It has since been reconfigured and now the electrical pump behavior is as expected. Upon turning it on, it builds up the pressure up to approx. 3.6 PSI and it stops by itself. When turned off, the pressure starts to decrease slowly.

    Thanks to all for providing valuable information that ultimately led to this finding.

     

    JC

     


    Thank you said by: RotaxOwner Admin

  • Re: PiperSport Electrical Fuel Pump

    by » 6 weeks ago


    Happy It all worked out and was something simple.

     

    Things like this is why I always say start with the most common, cheap and easy causes. Start at "A", then "B", then "C" and down the line and don't jump all over from "A" to "K" because sure enough it is usually something easy if you just follow good diagnostics in order.


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


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