Yep, you are right. Chieftain. Maybe that is what is causing the problem; the airplane is insulted.
It is also a lot warmer here this week, around +3C which is shirtsleeves weather and the airplanes love it too.
I operate many types of piston engine here, from round engines to Rotax, and the Chieftain engine is the only one that gives me grief. I can usually prime the heck out of a cold engine and it will start, but not this one. It seems to be very critical to having just the right amount of fuel. Too little and it will not fire, or will only cough. Too much and it will not start.
I would love to find a reliable priming or throttle setting to guarantee a smooth start and keep the boss happy.