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rough engine..

in 912 / 914 Technical Questions 13 years ago
I have a Rans with a 912 in it. It has 371the hrs on it since new. A couple of weeks ago I was climbing out of Riverside airport and about6 min into the flight the engine began running rough, When I said it was running rough in my head it tried to quit. I pushed the nose down to get a good glide speed. I also began to pull power to 4000Rpm, it came right back online and was smooth.
Flew it home with no other problems. It may have tried to vapor lock, not sure. Can anyone give me ideas where to start looking at problems. I was thinking of adding a facet fuel pump in line. Do I need one with a high wing. Any ideas would be great.

  • Re: rough engine..

    by » 13 years ago

    Do you have a fuel pressure gauge? Does your installation have the return line going back to your fuel tanks?

    I also fly a high-wing plane with a 912, and yes, it has an electric pump, too. I know many others that do, too. I have experienced low fuel pressures, and twice, a partial engine failure because of it. Both times, on climbout. Both times, engine went down to about 4000ish rpms, where it appeared to want to continue running. Once I turned on the pump, all was good again.

    The Rotax mechanical fuel pump on the 912, is well known to be the "best engineered, fool-proof fuel pump there is" (NOT!). If it was my plane, yes, I'd put an electric pump on it. A fuel pressure gauge, too.
      
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  • Re: rough engine..

    by » 13 years ago

    I do not have a fuel pressure gauge. Nor do I have a return line to the tanks. I do want to put a gauge in but I don't want to cut a hole in my nice panel.
      
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  • Re: rough engine..

    by » 13 years ago

    Rotax wants the return line in their systems. Of course, knowing your fuel pressure can be pretty important, too. If you had one, you might have been able to tell whether or not the problem you had was pressure related.
      
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  • Re: rough engine..

    by » 13 years ago

    I am looking at fuel pressure gauges. I will put one in for sure. How critical is the return line. Im thinking that would be very difficult to install.
      
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  • Re: rough engine..

    by » 13 years ago

    It shouldn't be all that difficult. Its just a hose going back from the fuel distribution block back toward your tank area. The installation manual shows a diagram of how they want it done. The whole purpose is to keep fuel moving, to reduce the potential for vapor lock.
      
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