Hello. I have a 912ULS with roughly 300 hours on a Powered Parachute. Lately it's been exhibiting a rough start behavior as follows:
1. Start engine from cold, half choke (I'm currently in AZ, start temps are generally 90-110° as it sits in an enclosed trailer under the sun). This is almost always a smooth start.
2. Warm engine up to 130°, taxi to end of runway
3. Kill engine to setup wing (parachute)
4. Start engine - rough start
Prior to about a month or so ago, the second start (step 4) was smooth, engine started, ran a bit slow until soft start advances the timing after about 2-3 seconds. Now, more often than not, it starts poorly the second time (that is, starter engaged more than a quick turn, maybe 2-4 seconds) and then seems to run rough on half the cylinders spitting and sputtering a bit, almost like it's flooded. After a few seconds it smoothes out and runs like normal. No issues in flight, all temps, pressures, etc nominal. Last night after we landed and killed the engine to pack up the wing, a restart exhibited the same behavior. However, once we taxi'd back to the trailer, I killed and restarted again and it was a smooth start with no sputtering. I don't know if that would be typical as I've not tried restarting once I've taxi'd to the trailer previously.
Mag checks during warm-up always result in a 60-100 RPM drop per side as expected. Fuel pump check same. No leaks, nothing out of the ordinary from a visual inspection. Plugs were changed about 60 hours ago. I've not pulled them to examine since then.
Any suggestions where to look? It's due for an annual in about a month, so I can have it looked at then, but thought I would see if I could make it better in the interim.
Thanks for any input.
