http://www.europaowners.org/gallery2/v/N914XL/Tri-Gear_Convert/ en-us Gallery 2 RSS Module, version 1.1.8 Wed, 22 Apr 2026 08:59:33 +0000 120 http://www.europaowners.org/gallery2/d/83640-5/Tri-Gear_Convert.jpg http://www.europaowners.org/gallery2/v/N914XL/Tri-Gear_Convert/ http://www.europaowners.org/gallery2/v/N914XL/Tri-Gear_Convert/IMG_3265.JPG.html http://www.europaowners.org/gallery2/v/N914XL/Tri-Gear_Convert/IMG_3265.JPG.html
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. ]]> rlborger photo Mon, 13 May 2013 22:14:57 +0000 http://www.europaowners.org/gallery2/v/N914XL/Tri-Gear_Convert/IMG_3577post.jpg.html http://www.europaowners.org/gallery2/v/N914XL/Tri-Gear_Convert/IMG_3577post.jpg.html
Next test, connect high pressure port from airbox directly to the "T" into the carb float bowl pressure lines and try a run. Still didn't work. Same smooth up to 4200/4300 RPM, smooth drop to 3200 RPM, smooth acceleration up to 4300 RPM, drop to 3200, repeat. Adding further throttle just makes the cycle faster and more violent. At this point I'm at a total loss for ideas. None of the support folks I was using for help seem to want to return my e-mail requests for assistance. The engine acts like there's no turbo pressure going to the float bowls or the float bowls are loosing the pressure. But there's no physical evidence for either case. A video showing the EIS readous of the last engine run is available, but at 2:19 it's pretty big so I don't want to upload. I don't know where to go from here.]]> rlborger photo Sat, 04 Aug 2012 19:09:24 +0000 http://www.europaowners.org/gallery2/v/N914XL/Tri-Gear_Convert/IMG_3571em_r.jpg.html http://www.europaowners.org/gallery2/v/N914XL/Tri-Gear_Convert/IMG_3571em_r.jpg.html
Pulled all the pressure hose off again and check for leaks and continuity. All OK, no problems at all.]]> rlborger photo Sat, 04 Aug 2012 19:09:24 +0000 http://www.europaowners.org/gallery2/v/N914XL/Tri-Gear_Convert/IMG_3540em.jpg.html http://www.europaowners.org/gallery2/v/N914XL/Tri-Gear_Convert/IMG_3540em.jpg.html
While the airbox was off, I again check all the pressure hoses to the carbs. Oh, what have we here. BIG leaks in the pressure lines to the carb bowls. Two leaks like this. Not observed before because the fittings were tied to that fuel line and the split was against the fuel line. The pressure line had to be removed to see the splits. Reason for split, use of an "inch" fitting instead of "metric" fitting. Stressed the hose causing the splits. Ordered new Rotax replacement fitting and new hose. All new parts fitted and checked. All OK. Ran engine. Still did not run right!!! Ran smooth up to 4200 RPM when RPM smoothly drops to 3200 RPM at which time it runs back up to 4200/4300 RPM and drops back down, repeat cycles.]]> rlborger photo Sat, 04 Aug 2012 19:09:24 +0000 http://www.europaowners.org/gallery2/v/N914XL/Tri-Gear_Convert/IMG_3538em.jpg.html http://www.europaowners.org/gallery2/v/N914XL/Tri-Gear_Convert/IMG_3538em.jpg.html
I removed the entire airbox to to check all the plumbing connections.]]> rlborger photo Sat, 04 Aug 2012 19:09:24 +0000 http://www.europaowners.org/gallery2/v/N914XL/Tri-Gear_Convert/IMG_3438em.jpg.html http://www.europaowners.org/gallery2/v/N914XL/Tri-Gear_Convert/IMG_3438em.jpg.html
There was a bit more work with the Billet pump package, but it proved not to be the problem. Moving on, OK, not the fuel system. Try running the engine as a normally aspirated engine. Remove the connection between the turbo and airbox. Believe it or not, the engine ran perfectly. Smooth as silk from 2000 RPM up to 5600 RPM where it stalled out on the prop pitch. Looks like the issue is in the turbo boost somewhere.]]> rlborger photo Sat, 04 Aug 2012 19:09:24 +0000 http://www.europaowners.org/gallery2/v/N914XL/Tri-Gear_Convert/IMG_3391em.jpg.html http://www.europaowners.org/gallery2/v/N914XL/Tri-Gear_Convert/IMG_3391em.jpg.html
Input fuel pressure: 5 lbs. Just like with the Billet pump. Next request was for a fuel flow test. Reconnected the Billet pump to the fuel circult. One electric pump running fuel through the billet pump produced 1 gallon of fuel in a bit less than 3 minutes or about 20 gal/hr. Should be plenty of flow, no restrictions.]]> rlborger photo Sat, 04 Aug 2012 18:44:00 +0000 http://www.europaowners.org/gallery2/v/N914XL/Tri-Gear_Convert/IMG_3392.JPG.html http://www.europaowners.org/gallery2/v/N914XL/Tri-Gear_Convert/IMG_3392.JPG.html
Differential pressure with engine running on electric pump: 3.8 lbs]]> rlborger photo Sat, 04 Aug 2012 18:44:00 +0000 http://www.europaowners.org/gallery2/v/N914XL/Tri-Gear_Convert/IMG_3384em.jpg.html http://www.europaowners.org/gallery2/v/N914XL/Tri-Gear_Convert/IMG_3384em.jpg.html
Remove the Billet pump from the circuit. Run with only electric pump. Input line connected directly to the regulator. At the same time, remove airbox pressure from differential gauge to get absolute fuel pressure out of regulator.]]> rlborger photo Sat, 04 Aug 2012 18:44:00 +0000 http://www.europaowners.org/gallery2/v/N914XL/Tri-Gear_Convert/IMG_3374em.jpg.html http://www.europaowners.org/gallery2/v/N914XL/Tri-Gear_Convert/IMG_3374em.jpg.html
Run the engine, check the pressures. All seems OK. 5 lbs into the regulator and 3.8 lbs out of the regulator. This is with the Billet mechanical pump. Which became the next source of concern.]]> rlborger photo Sat, 04 Aug 2012 18:44:00 +0000