Carb problem

[KevinC]

I am having a problem with the left side carb porting fuel out the vent line.  Here are the facts:

rotax 912ULS, <3 hrs total time
using premium unleaded
fuel is clean (I checked strainer, sumps and float bowl)
needle valve stops flow (at least when engine is not running)

and the observations (not necessarily facts):

seems to be most associated with when the carbs are out of sync (during adjustment, when one cable adj jamb nuts came loose and when one carb cable came loose).
When engine is running smooth and sync'd, no porting fuel.

thanks all!

K

[alan]

I wonder if it might be slopping out when the engine is shaking/vibrating because of the out of sync condition?

alan

[KevinC]

I think Alan was right.  I found 3 references online that suggest a rough running engine would lead to porting fuel out the vent.  We sync'd the carbs again and had no fuel leaking with a smooth running engine.

For those who may follow, here's where I found the best reference material:  http://www.rotaxservice.com/rotax_tips/ ... ration.htm
There is a good Powerpoint presentation on the whole subject of vibration.

K