johnm Posted October 3, 2012 Share Posted October 3, 2012 Boffins with a rotax 912 (about 700 hours) - high wing aeroplane - with the fuel cocks left on .............. the passenger side air cleaner is saturated with fuel (over say a 2 day period) and there is a small quantity of fuel on the fuel tray this leads to a rough start - lots of fuel one side - not the other have replaced the internal horizontal float pins and the rubber seat valves - but problem still persists (might need a closer look at the seat valve again) is there any other reasons for fuel on the fual tray ? thanks Link to comment Share on other sites More sharing options...
facthunter Posted October 4, 2012 Share Posted October 4, 2012 Usually the float needle seat. There could be sediment in the fuel that is affecting the seat. Fine filters can help there but they can block. How level is the carb when the plane is parked? The only sure way to prevent this is to turn the fuel OFF. ( Then you must make sure to turn it ON, later) Nev Link to comment Share on other sites More sharing options...
johnm Posted October 5, 2012 Author Share Posted October 5, 2012 thanks FH we'll bore in on the seat and will check level in the hangar Link to comment Share on other sites More sharing options...
Spriteah Posted October 21, 2012 Share Posted October 21, 2012 Thats a very interesting problem. Please keep this thread updated so we all can learn from your issue. Jim Link to comment Share on other sites More sharing options...
johnm Posted October 30, 2012 Author Share Posted October 30, 2012 problem fixed ! .......................... and 'lil old motor runs smooth as facthunter suggested - it was the seat - photo is underside of the top portion of carb - the circular brass thing is the seat cleaned / lapped ? all this up - valve now seals against the seat why did the rubber seal and seat leak in the first place - don't know what caused the scratches on the seat - don't know (at attempt 2 a cotton bud was used to lightly clean the seat) 1 Link to comment Share on other sites More sharing options...
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