Engine surging / rough running
in 912 / 914 Technical Questions
5 years ago
A few weeks ago my plane (Rans S-19) had its maiden flight. Just after it became airborne the engine began to surge. A Rotax engine specialist visited and detected the the overflow line from the airbox was venting at a position that was too low - about 2 inches below the firewall - and was experiencing a ventuir effect from the propellor slipstream. That problem was easily fixed but the engine then began to run very rough. This time the problem was rubber contamination in the carby bowls, especially the right side though the needle jets seemed clear. I'm not sure where the source is. The gascolator is on the firewall and it's clean. I blew all my rubber hoses out with compressed air before installation so I'm wondering if vibration of the rubber fuel lines on the fuel line barbed fittings would be enough to cause this?
My main question: I had somebody with me the other day who works on car engines. He asked why fuel filters weren't installed just before the carbys given that sort of contamination in the bowls can be a real show stopper. The only answer I could think of was "nobody seems to do this" and I would prefer to eliminate the problem at source but if it's going to be a recurring problem I'm wondering if it might be a good suggestion? I could wrap them in firesleeve. Any thoughts?
Thanks,
Chris
My main question: I had somebody with me the other day who works on car engines. He asked why fuel filters weren't installed just before the carbys given that sort of contamination in the bowls can be a real show stopper. The only answer I could think of was "nobody seems to do this" and I would prefer to eliminate the problem at source but if it's going to be a recurring problem I'm wondering if it might be a good suggestion? I could wrap them in firesleeve. Any thoughts?
Thanks,
Chris
