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Thread: Carb flooding and venting, Kitfox4 912 UL

  1. #11

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    Default Re: Carb flooding and venting, Kitfox4 912 UL

    Quote Originally Posted by jiott View Post
    Before replacing the carbs, I would suggest you replace the little rubber-tipped needles AND the seats in both carbs. Very likely they are worn and don't seal well at the normal fuel pressure.
    The rubber tipped needles were replaced. Lockwood said it might be the seats. Whether or not they could repair them, they said, was not guaranteed.

    Thanks,
    Bob

  2. #12
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    Default Re: Carb flooding and venting, Kitfox4 912 UL

    I've replaced the seat on a Bing type 94 carb without problems. Made a puller, ran threads into the seat/jet, and pulled old one out. Pressed new one in. I did this so I could run my Jabiru with gravity feed. JImChuk

  3. #13
    Administrator DesertFox4's Avatar
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    Default Re: Carb flooding and venting, Kitfox4 912 UL

    My question is why not reinstall the fuel pressure regulator as it solved this issue for the previous owner? It’s initial installation tells me the fuel pump is over pressurizing the carbs.
    If your fuel pump is putting out too much pressure to the carbs, they will overboard fuel regardless of the needle color or condition or how many internal parts you changed in the rebuilds.
    What’s going to really make you angry is spending a boat load of money on new carbs and solving nothing. While a pressure regulator may be non-standard on the majority of the Rotax installation, some of Rotax’ mechanical fuel pumps produce more pressure than the carbs can handle. If it ran for many trouble free hours before, it should again if you restore it to it’s previous configuration. If you still have that regulator, put it back in where it was before with the original fuel pump and give it a try. Too many changes at once and you will never know what solves the issue or worse, nothing was solved.
    If that regulator bugs you being in the fuel system, try a new fuel pump first. Lots less money compared to new carbs or even used carbs that you may have to rebuild anyway. Do the simple things first. Frustration costs money and time.


    DesertFox4
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  4. #14
    Senior Member Slyfox's Avatar
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    Default Re: Carb flooding and venting, Kitfox4 912 UL

    I agree put the pressure reg back on. If you really want to know what's going on, check the fuel pressure before the carbs. that will tell all
    steve
    slyfox
    model IV 1200-flying
    912uls
    IVO medium in-flight
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  5. #15

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    Default Re: Carb flooding and venting, Kitfox4 912 UL

    Quote Originally Posted by DesertFox4 View Post
    My question is why not reinstall the fuel pressure regulator as it solved this issue for the previous owner? It’s initial installation tells me the fuel pump is over pressurizing the carbs.
    If your fuel pump is putting out too much pressure to the carbs, they will overboard fuel regardless of the needle color or condition or how many internal parts you changed in the rebuilds.
    What’s going to really make you angry is spending a boat load of money on new carbs and solving nothing. While a pressure regulator may be non-standard on the majority of the Rotax installation, some of Rotax’ mechanical fuel pumps produce more pressure than the carbs can handle. If it ran for many trouble free hours before, it should again if you restore it to it’s previous configuration. If you still have that regulator, put it back in where it was before with the original fuel pump and give it a try. Too many changes at once and you will never know what solves the issue or worse, nothing was solved.
    If that regulator bugs you being in the fuel system, try a new fuel pump first. Lots less money compared to new carbs or even used carbs that you may have to rebuild anyway. Do the simple things first. Frustration costs money and time.
    As we began the whole process of replacement, we saw the regulator and a fuel filter on the line from the pump to the carb. At that point we checked with Lockwood and asked if that was a standard setup, or necessary. According to them, it was neither. The carb was supposed to be, designed to be, happy with the pump, unfettered. When the new carbs are installed, we will have the fuel system pretty much as it came from the factory. I hope it works.

    Thank you for your reply.
    Bob

  6. #16
    Senior Member Slyfox's Avatar
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    Default Re: Carb flooding and venting, Kitfox4 912 UL

    standard procedure for diagnosing this problem is to do a fuel pressure test anything short of that and you are throwing your money out the window. sorry I don't believe in your way of fixing something.
    steve
    slyfox
    model IV 1200-flying
    912uls
    IVO medium in-flight
    RV7A-flying
    IO-360
    constant speed prop

  7. #17

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    Default Re: Carb flooding and venting, Kitfox4 912 UL

    That's what makes the world go round.

    Thanks for the reply,
    Bob

  8. #18

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    Default Re: Carb flooding and venting, Kitfox4 912 UL

    Hi Bob,

    I have been struggling with carb flooding and venting also.

    I was curious if the new carbs solved the problem?

    Charles

  9. #19
    Senior Member Dusty's Avatar
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    Default Re: Carb flooding and venting, Kitfox4 912 UL

    When I replaced my old engine with a new one i had flooding and venting issues.
    Everything was as per rotax spec but the fuel pressure was higher (7 psi vs my old pump 5 psi)
    I think these issues were a combination of high fuel pressure and ground angle with Bush wheels and extended gear .

    My solution was to replicate the setting off my old motor. The pump was modified to provide 5 psi(with no return line). I also lowered my float level by1/8 of an inch with no difference in running or egt in flight. Before I lowered the levels I couldn't taxi upslope without rough running and black smoke. 270 trouble free hours later

  10. #20

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    Default Re: Carb flooding and venting, Kitfox4 912 UL

    Quote Originally Posted by cwsnyder2001 View Post
    Hi Bob,

    I have been struggling with carb flooding and venting also.

    I was curious if the new carbs solved the problem?

    Charles
    No, the new carbs did not solve the problem. Today, my mech put in a gauge and checked the pressure of the new fuel pump which I installed. It is 6.5 psi using the starter. He thinks the problem may have to do with the angle of the a/c as a taildragger; ie, the floats not seating properly because of the angle, about 13 degrees. Tomorrow, he and I will put the old Mr Gasket fuel pressure regulator the previous owner had on the line from the pump to the carbs. We will read the pressure it shows. Then we plan to remove it and put a new Mr Gasket regulator in its place and match the pressure. We think the cabs would work normally, and do in an inflight, level attitude. But, you can't taxi and take off with the gas dripping out all over. I'll let you know how it goes.

    As you can imagine, we've talked to a bunch of folks from Kitfox and Lockwood. Lots of scratching of heads at both places.

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