912ULS Rough Start After Warm-Up and Shutdown

Sean Griffin wrote:

Sounds like hot fuel/vaporisation.

If you have a fuel return system, run the boost pump until a steady pressure is achieved. This should reduce the amount of vapour/bubbles in your fuel delivery system. Start engine. There may still be a short rough period.  Leave pump on until you reach a safe altitude.

😈

Hi Sean.  I tried this - left the pump on for about 15 seconds prior to ignition, but it didn't seem to help.  Unfortunately I do not have a fuel pressure gauge, so I've no way of monitoring it.  I will however continue to engage the pump for 15 to 20 seconds from now on as a precautionary item.  Thank you.

Rotax Wizard wrote:

The current government has passed "wavers" for states to sell winter gas into the hot summer months.  (oil supply issues) I would try some avgas, up to 50%, mixed in.  This should minimize any vapour lock issue if that is the problem. 

Cheers

Ah yeah.  Good point.  I'd actually not considered this.  From Michigan, in AZ from Nov to April and have been using top tier mogas that whole time (which I do in MI also).  I'll do a 50/50 mix next flight to rule that out.  Thank you!