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So I thought I finally joined the club. As I was bragging earlier in this thread about having my original floats with 1000 hours. and they weighted less that 6g per set. Well within spec. and working fine. The other day on a flight I felt a little shudder in the engine in cruise flight and the smell if fuel. OK I know what that is. I got it to do it again on the runway after landing. So I removed the floats and weighted them just like before they weight good on a calibrated reloading scale. 2 @ 3g and 2 @2.8g. So I checked float level it was in spec. I could not make them over flow with the electric pump on at 3 psi. So thought the mechanical fuel pump was having short burst of higher PSI than it should . I never caught that on the dynon. My fuel pump(newer style) had 700 hours on it so I replaced it. No good same symptom's. Ok now I replaced the float valve and float bracket and the floats. Then set level to spec. I also replaced the diagram's all though to old ones looked good, No good same symptom's. This is a totally intermittent problem . The one constant is it happens after I have been flying for between 30 and 45 minutes No other time. After I get it back on the ground after this happens I can get it to really drop rpm and shake like **** with fuel smell and fuel on the drip pan. So where do I go from here. I am beginning to think its not a carb problem at all. It seems to be heat related . It always starts and runs very smooth and the carbs are in perfect sync. I am wondering if maybe an intermittent loss of ground on the ignition system after warming up?? This would might cause shaking and vibrating that makes to bowls overflow causing the fuel smell and bowl overflow. So I saved my original floats with 1000 hours. I never replaced them for fear of getting bad ones like many others on this forum. Any ideas guys. Thanks Brad Stiefvater Salem SD n124bj first customer built 12 to be airworthied and fly maiden flight 9-20-2009

  • Re: need help with this one.

    by » 6 weeks ago


    Maybe you are picking up some carburetor ice, which would explain the intermittent issue.

     


  • Re: need help with this one.

    by » 6 weeks ago


    This is on an RV 12 with enclosed cowl. Icing would be unlikely as I have flow 1044 hours in all different conditions winter and summer and never an issue.  My last test 3 flights where all in different weather condition's. Actual one of the times it did this was after setting at an airport for 30 minutes . then it happened briefly on startup. It can get pretty hot under the cowl after shut down.

     

     

       Thanks for the reply I wish it was carb ice I know how to deal with that.

     


  • Re: need help with this one.

    by » 6 weeks ago


    Have you verified there is no debris in the float bowls/jets?


  • Re: need help with this one.

    by » 6 weeks ago


     

    yes no debris.

     

    I little more info here. I was on a test flight yesterday and every thing was smooth and perfect. Then I notice a slight stumble didn't lose and rpms but I noticed the left EGT drop 150 degrees then recovered in seconds. So OK get back on the ground. So I tried to replicate the failure and I got it to fail again this time the right EGT dropped suddenly by 600 degrees. Flooding and shaking like **** . The fuel flow went to 10.5 GPM.

    I have been doing mag checks through out all PRM ranges for the last three weeks of this search and all where perfect.


  • Re: need help with this one.

    by » 6 weeks ago


    also my first post was a little confusing . I did not put the 1000 hour floats back in. I just saved them in the cabinet.

    I am using new the new floats along with all the other new parts I mentioned


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