fbpx

 

Hello all.

 I have a 912UL on a Skyranger I finished building earlier this year. I flew approximately 30 hours on it without any problems. It was then noticed that the port carb was flooding and on inspection that the float valve was not seating correctly and shutting off the fuel when it should. This was re seated. Ever since then, starting immediately, I have intermittent loss of power when on full throttle. At the point where the power loss occurs I have shut down quickly and found that the fuel level in the port carb is very low, the starboard bowl is full. The port carb has been stripped down and inspected by a proffesional and no fault found but still the problem persists!

 

The fuel pressure has been checked and a fuel flow test carried out.

 

I am now thinking that the float valve is intermittently sticking closed and causing the problem but I'm by no means sure. I would appreciate peoples thoughts on this please.

Thank you.

 

  • Re: Fuel Starvation, no apparent cause!

    by » 7 months ago


    Could you have a blockage on the fuel hose to the carb?

    What if you did the following when you have the problem: disconnect the fuel supply hose and try blowing into it. If the floats are down (low fuel level) and the needle valve is stuck shut then you will not be able to blow into the bowl. If this is the case then you could carefully remove the bowl, check that the needle valve can be moved and try blowing into the fuel supply hose again, if you can then the valve is sticking, if you can't then you have a blockage.


  • Re: Fuel Starvation, no apparent cause!

    by » 7 months ago


    What did the spark plugs look like?  Were they light grey as if they had been running lean?  One of my carbs was doing that same thing and the engine would cut out only at wide open throttle. Plugs on that one side were grey.  I discovered that the float arms in that carb were not set quite parallel to the carb flange per the manual and more interestingly the two float arms had been squeezed in towards each other slightly but it was enough to rub on the carb body and cause fuel starvation at high rpm.  This bend inward was very slight and was easy to miss so look close and see if the arms move freely up and down without contacting anything near by with the bowl off.  When the arms on my carb were set to the right parallel dimension and unbent inwardly the float valve was free to do its job and the problem went away.  


  • Re: Fuel Starvation, no apparent cause!

    by » 7 months ago


    Maybe it is vapor lock, do you have a return line?


  • Re: Fuel Starvation, no apparent cause!

    by » 7 months ago


    The fuel lines from the tank to both carbs have been replaced entirely with no effect


  • Re: Fuel Starvation, no apparent cause!

    by » 7 months ago


    Yes a return line is installed. Larry Olson, was your fuel starvation intermittent or constant? My float arms do seem to move up and down freely with the bowl off and the carb has been stripped and inspected by a proffesional but they could have missed something. Did you use the proper gauge to set your float arms or just tweek them by hand to how you thought they should be?

     


You do not have permissions to reply to this topic.