IMG_3265

Herein lies the culprit! The change from flat fiber washer to "O" ring. When the "O" ring is applied to the attachment screw and tightened to the torque spec, the bottom of the fuel bowl is deformed upward. This deformation reduces fuel flow to the jet causing fuel starvation. This was discovered by Nathan Probst over at USAviation. He corrected the deformation of the fuel bowl and reassembled such that the "O" ring seals but the bowl is not deformed. Since then, Rotax has come out with a new Attachment Screw ($$$) which is supposed to correct the problem.