Kitfox Aircraft Stick and Rudder Stein Air Grove Aircraft TCW Technologies Dynon Avionics AeroLED MGL Avionics Leading Edge Airfoils Desser EarthX Batteries Garmin G3X Touch
Page 4 of 4 FirstFirst 1234
Results 31 to 34 of 34

Thread: Carb flooding and venting, Kitfox4 912 UL

  1. #31
    Senior Member Slyfox's Avatar
    Join Date
    Dec 2008
    Location
    felts field, spokane
    Posts
    1,327

    Default Re: Carb flooding and venting, Kitfox4 912 UL

    I'm going to hit one more thing on all this mess. I read all the time about how bad the carb floats are on the 912. There is a huge discussion on the Vans list about this. Rotax says to weigh the floats. Well I for one want to see a sinking float. I always check my carbs at oil change, meaning I remove the bowl and be very careful to keep the level of fuel high. I than set the bowl on a flat surface and look at the floats, a sinking float will show you a sinking float. I've read oh man I weighed my floats and they are over what rotax calls for, well let me tell you, I've tried to weigh my floats and got varied results. Tough to do. I go by sight. I think most people with flooding carbs are in fact having over pressure problems. Now I'm not right there looking at things and testing so I can't say for sure. My thought is if your running over 4.5 psi than change it. Also for someone to say that adding a regulator is out of sorts , well so be it. I think a person should be making things right whatever it takes. I've personally seen these new fangled pumps that rotax put out just plain put out too much psi to the carbs. my take, take it or leave it. I know what I'm doing with mine and that's what matters. my rotax runs like a million bucks.
    steve
    slyfox
    model IV 1200-flying
    912uls
    IVO medium in-flight
    RV7A-flying
    IO-360
    constant speed prop

  2. #32
    Senior Member Dave S's Avatar
    Join Date
    Oct 2008
    Location
    St Paul, MN
    Posts
    1,833

    Default Re: Carb flooding and venting, Kitfox4 912 UL

    Thanks for your comment on the floats, You are SPOT on.

    The practical way to determine if they are OK or not is seeing how high they ride in the gasoline after carefully pulling the bowl without spilling - if the little brass protrusions on the sides of the floats are level with the fuel - they are correct.

    The problem with weighing which can scatter the results all over the place is because of varying amounts of evaporation that occurs between taking them out of the bowl and getting them on the scale. Air movement, temperature and time can all mess up an accurate weighing as varying amounts of fuel go away.

    The floats unmolested height in the fuel is an accurate real world function. What you said.
    Dave S
    Kitfox 7 Trigear (Flying since 2009)
    912ULS Warp Drive

    St Paul, MN

  3. #33

    Join Date
    Oct 2020
    Location
    Camp Hill, PA
    Posts
    12

    Default Re: Carb flooding and venting, Kitfox4 912 UL

    Quote Originally Posted by cwsnyder2001 View Post
    Bob,

    Just following up with my end results.

    I installed the new pump (893115, same as the old pump), with an analog gauge, fuel regulator and another analog gauge in the pump output line. Carbs are balanced.

    The new pump still pulsated as expected but the pulsations were not as extreme. With the regulator at maximum pressure (7 psi), approx. 5.5 psi was seen at the carbs.

    Like you experienced, I was still getting overflowing at idle.

    I lowered the regulator in half psi increments until the overflowing stopped (3 psi) and I ran the engine through the entire rpm range with the pressure varying from 3 to 3.5 psi.

    The regulator stays.

    Charles
    We placed the new regulator in line to the carbs. It reduced the pressure to 4psi. No leaking carbs, only occasional slight drips from the vent line at idle. I've flown about 3 hrs this setup. Engine runs well.

  4. #34
    Senior Member Slyfox's Avatar
    Join Date
    Dec 2008
    Location
    felts field, spokane
    Posts
    1,327

    Default Re: Carb flooding and venting, Kitfox4 912 UL

    Quote Originally Posted by Dave S View Post
    Thanks for your comment on the floats, You are SPOT on.

    The practical way to determine if they are OK or not is seeing how high they ride in the gasoline after carefully pulling the bowl without spilling - if the little brass protrusions on the sides of the floats are level with the fuel - they are correct.

    The problem with weighing which can scatter the results all over the place is because of varying amounts of evaporation that occurs between taking them out of the bowl and getting them on the scale. Air movement, temperature and time can all mess up an accurate weighing as varying amounts of fuel go away.

    The floats unmolested height in the fuel is an accurate real world function. What you said.
    Yes I have had 2 floats now since 2004 that sunk. I will always believe that the only way to know, and that's how I found those two floats, is to remove the bowl and look at the float. Back in the old days we use to always find a carb float on a vehicle that was bad by doing that. take care.
    steve
    slyfox
    model IV 1200-flying
    912uls
    IVO medium in-flight
    RV7A-flying
    IO-360
    constant speed prop

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •