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Thread: Fuel System OverPressure 912IS

  1. #1

    Join Date
    Sep 2016
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    Default Fuel System OverPressure 912IS

    First significant post after purchasing an S7 w 912iS (N52LR) a few months ago. I have been putting some good flight time in and getting comfortable with the plane. Love it so far. I have been flying since 79 with time in many planes, but primarily an SR22 I sold a few months ago. I really like this kind of flying.

    A couple of weeks ago shortly after takeoff I got a fuel high pressure warning. At the time I had the main pump running and full power. I throttled back and it bumped up to the red and the Lane A light came on solid. Shortly after the Dynon suggested to land the plane. I was not far from the runway and landed without incident.

    I was able to communicate with the builder and review the fuel system. The filter system is relatively new based on the recommendation from Kitfox/Rotax. It was installed in March of this year and has somewhere near 30 hrs on it.

    I found what looked like an oil drip coming from the fuel pressure sensor. I was able to pull both fuel filters. It was kind of a mess, could not figure out how to drain the system to keep everything from leaking when disconnected. I let the large post pump filter drain as best I could and captured the fuel. There was some very fine particles suspended in the fuel. I lightly blew in the end and it held pressure for a couple of seconds then gave way. It seemed clear after that. I could not see a way to open the filter. When pulling the pre-pump filter it looked pretty clear.

    I put everything back together and checked the pumps. Everything seemed to be fine. The pressure holds around 44-45. I did a full power start / roll out and pulled the cowl. No leaks. Then took it up in the pattern for 20 minutes. All good.

    With all that said I have a few questions for the experts.
    1) Should I replace the post pump filter? Does anyone know the replacement?
    2) That seems like a very short time for the filter to get stopped up, assuming that is the issue. Anyone else seeing this?
    3) I am assuming the post pump filter is the source of the trouble. Anything else it could be?

    How many have updated the filter system?

    Thanks in advance for any help and support.
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  2. #2
    Senior Member efwd's Avatar
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    Default Re: Fuel System OverPressure 912IS

    Put some funky fuel in it or have debris from the manufacture of the fuel system and one can plug a filter the day it is run the first time.
    Kitfox part number for that 8 micron fuel filter is 98242.000 according to my 912iS FWF installation manual.
    Eddie

  3. #3
    Senior Member
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    Default Re: Fuel System OverPressure 912IS

    Hi Paul,

    I have a 912is sport with the Kitfox FWF kit. I have 311hrs now and have changed out the fine filter 3x at the 100hr services. The fine filter I use is Genuine OE BOSCH 0450905021 / F5021 Fuel Filter

    If you have the Kitfox fuel manifold, then when the fuel pressure increases to beyond the recommended pressure, it indicates that the fine filter is becoming blocked - however, the bypass valve will continue to supply fuel to the engine by bypassing the filter - a nice feature that gives you a pretty good margin of safety to land and change the filter out.

    You have already found out that the course filter ( or pre pump filter) is able to be dismantled and cleaned whereas the fine filter ( post pump) is not serviceable - therefore you must replace it. I carry a spare.

    Hope this helps

    cheers

    Ross
    Ross
    Mt Beauty, Vic
    OZ
    Sold to Richard and Scott Taubman in OZ, 2019. Kitfox SS7,Rotax 912is Sport, Airmaster CSP 75" blades.
    Landcruiser and Cub off road camper (doesn't get any kudos on this forum!)

  4. #4

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    Default Re: Fuel System OverPressure 912IS

    Thanks for the feedback. That is what I was hoping to hear. I did study the system and figured out the bypass valve. That likely kicked in when the pressure shot up, but it was hard to tell. As you say it is nice to know the fuel flow won't simply stop. And it was interesting to see the Dynon tell me to land. That system is every bit the equal of what I had in the Cirrus.

    I will just buy a few and have them ready when the pressure starts to work up.

  5. #5
    Senior Member
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    Default Re: Fuel System OverPressure 912IS

    Yes Paul, I just order a few on line at a time and change them out ever 100 hr. I haven't had the prob you had but never know when you are going to pick up some rubbish in the fuel. And yes, the 912is system takes a bit of understanding and the warnings too. For instance, I went to start up recently and had a solid Lane B light - My EMS told me the EGT sensor was over heat ( although the engine was not running!) - obviously a sensor. Relatively easy fix ( expensive !) but what I didnt know and have since learned is that the EGT sensor info is not used by the computer to adjust fuel mixture - so it would have been fine to fly home if it happened somewhere. Apparently the system checks the injectors for that pot to make sure they are ok. I would carry a spare of them to but at $270 each I think that is a bit extreme!

    good flying

    r
    Ross
    Mt Beauty, Vic
    OZ
    Sold to Richard and Scott Taubman in OZ, 2019. Kitfox SS7,Rotax 912is Sport, Airmaster CSP 75" blades.
    Landcruiser and Cub off road camper (doesn't get any kudos on this forum!)

  6. #6
    Senior Member jiott's Avatar
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    Default Re: Fuel System OverPressure 912IS

    Regarding the EGT sensor, if I haven't run the engine for 4-5 days when I startup the left side sensor almost always shows the red cross or a very high overtemp condition on my screen. I have learned to ignore it because in a few minutes of warmup it starts reading correctly and stays correct for the rest of the day. I have taken it out and cleaned it and checked the wiring but it has continued to do this for several years now. Probably should replace it; the right side never acts up.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

  7. #7

    Join Date
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    Oak Harbor,Wa
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    Default Re: Fuel System OverPressure 912IS

    I also have the Kitfox fuel filter manifold and new filter arrangement. I have had the fine filter become clogged and get the high filter warning. I change the filter and all is well. Like Rossir I keep at least spares on hand and on any cross-country trip I carry a spare filter and a spare EGT sensor.

  8. #8
    Senior Member jdmcbean's Avatar
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    Default Re: Fuel System OverPressure 912IS

    We do keep the filters in stock if you're looking for them.
    John McBean
    www.kitfoxaircraft.com
    208.337.5111

    "The Sky is not the Limit... It's a Playground"

  9. #9

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    Default Re: Fuel System OverPressure 912IS

    Thanks John, just ordered them yesterday.

  10. #10

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    Default Re: Fuel System OverPressure 912IS

    Regarding EGT's, it was a constant issue with the Cirrus. It got so bad that people started ignoring them. But it was easy to dismiss when the EGT would peg out and then drop back in a few seconds.

    With the Cirrus it was a connection issue. The connectors were junk. There was a guy who offered a package to replace them. It would usually eliminate the problem.

    On the Rotax do they simply fail or is it a connection?

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