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Thread: engine problems 912 UL

  1. #1

    Join Date
    Aug 2009
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    Holland
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    2

    Default engine problems 912 UL

    Who can help me to solve my engine problems?
    After 1 year no flying my 912 UL runs very rough beyond 4000 RPM. When I pull the choke the RPM go up to 5000. Looks like too lean mixture, so I thoroughly cleaned tanks, all fuel lines and carburators. Inspected carbs according to heavy maintenance manual, and could not find anything wrong. Fuel flow is ok and fuel pressure also ok. But engine still runs just as rough.
    Before this problem the engine has run fine for 200 hours.
    Compression is ok, and ignition L, R or both does not make much difference. Asked many AMTs here and they don't know more than I do.
    Who can get me into the Dutch air again?

  2. #2
    Senior Member
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    Pittsboro,NC
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    Default Re: engine problems 912 UL

    Hey Thom, Did you sync your carbs? If they're out of sync they will cause all sorts of vibration and rough running. Good luck, James Thomas

  3. #3
    Senior Member Slyfox's Avatar
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    Default Re: engine problems 912 UL

    the carbs are very picky about getting the bleed holes plugged up. My advice, take the bowls off and remove all jets. Than take off the air filter. Than take some carb cleaner(spray) and hit every little hole you find. Than you will need to remove the top cover and check the diaphram for cracks. If this doesn't do it, than send the carbs out to lockwood and have them rebuild them. Really sounds like thay are pretty gummed up.
    steve
    slyfox
    model IV 1200-flying
    912uls
    IVO medium in-flight
    RV7A-flying
    IO-360
    constant speed prop

  4. #4
    Administrator DesertFox4's Avatar
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    Default Re: engine problems 912 UL

    Thom, just went through something like you described on a friends freshly overhauled 912. He never touched the carbs or settings when he removed the engine for overhaul. Bolted both carbs back on (new carb boots were installed) and went through the sync procedure and it would not run above 4500 rpms. Ran nice a smooth at anything under 4500 rpms. Checked float levels and fuel flow rates. All were right. Still no good. The only thing I could think of was it was not getting enough fuel at the higher power settings. I had him turn out (open) his high speed jet setting by a half turn on each carb. Normal setting is 1.5 turns out from closed. We went to 2 turns out on both carbs and instant success. Try that after checking the items already mentioned. It may just be too lean on the high power settings. I hope it's that simple. Keep us posted please on your solution. Good luck.


    DesertFox4
    Admin.
    7 Super Sport
    912 ULS Tri-gear


  5. #5
    Senior Member SkySteve's Avatar
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    Jun 2008
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    Huntsville, UT
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    Default Re: engine problems 912 UL

    Desert Fox, we are having this exact same problem with a Kitfox 4 here in Utah. We have been working on it for days. Changed the fuel, fuel lines, fuel filter, new carbs, checked wiring and still the same. Runs fine on ground but on take off it sputters and quits at 5,200 - 5,400 RPM. Had to set it down twice yesterday on take offs. HELP. We don't understand what you mean by "high speed" adjustments. This is a 912 80hp. We are at the hangar now working on it trying to get it to the fly-in. Call us if you can. 801-791-4777.
    Steve Wilson
    Huntsville, UT
    Kitfox 85DD
    912A / 3 Blade Taper Tip Warp Drive
    Convertible Nosewheel & Tailwheel
    SkySteve's SPOT Page
    SkySteve's You Tube Videos

  6. #6

    Join Date
    Aug 2009
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    Holland
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    Default Re: engine problems 912 UL

    Thanks guys. Took carbs apart again and blew compressed air through all holes. O-rings on main jet/mixing tube were not perfectly round and I replaced these. And guess; it now runs perfectly well, just as before. Turning idle mixture screw did not make difference. I'm in the air again.

    The rough running caused collateral damage: one ignition intermittently quitted. This was caused by cracked wire from the charge coil (one of the 2 red wires) that go to the black ignition boxes.

    Greetings from Holland.

  7. #7
    Senior Member Slyfox's Avatar
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    Default Re: engine problems 912 UL

    fantastic. I generally do the bleed hole blow outs about every other oil change. I don't take the carbs off to do this though.
    steve
    slyfox
    model IV 1200-flying
    912uls
    IVO medium in-flight
    RV7A-flying
    IO-360
    constant speed prop

  8. #8
    Senior Member
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    May 2009
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    Lethbridge, Alberta
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    Default Re: engine problems 912 UL

    moral of the story ....don't wait for a year before you go flying. great to hear your up and flying.

  9. #9
    Senior Member akarmy's Avatar
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    Default Re: engine problems 912 UL

    Can you give us a bit more on the "procedure" to blow out the bleed hole?
    Andy Karmy
    Kitfox 7 - 912S - SOLD
    Auburn, WA

    http://kitfoxflying.com

  10. #10
    Senior Member Slyfox's Avatar
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    Default Re: engine problems 912 UL

    Nothing to special, I just remove the bowl, than I remove all the jets, idle mixture-mid range jet and main jet. Than I take a can of carb cleaner with the extension and shoot into the carb through the holes. Than I take a low volume air gun with my compressor and shoot into the holes again. Make sure the filter is off and that carb cleaner and compressed air comes out of the real small hole when doing the mid range jet, this one is the most important. That I turn the fuel on(make sure it's off when you start) to make sure there isn't anything in the float valve. Than I squart some carb cleaning in there as well. I'm done. Put everything back to gether and run er.
    steve
    slyfox
    model IV 1200-flying
    912uls
    IVO medium in-flight
    RV7A-flying
    IO-360
    constant speed prop

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