Ratman nailed it regarding temperature sensitivity on the TC version. Well, it might be a couple things that need adjusting to be ideal. Procedure is to crack the throttle 1/4 in. and increase mixture to full rich to achieve > 5 GPH. Two things look to be working against trying to achieve that.
Fuel flow does not increase based on throttle setting until the throttle is up to around 80% and higher, thus cracking it 1/4 in., or even 50% open, is no different than keeping it fully shut off in terms of fuel flow and starting the plane. You just need some fuel flow during prime to start.
On the TC version fuel flow is dependent on outside temperature. The TC version looks to behave like the normally aspirated version at ~54F, where fuel flow peaks, and at temps below. As temp increases from 54F, fuel flow starts to drop when priming. Since its pretty damn hot all over the northern hemisphere right now, if you fly real world conditions, you're probably at > 75F on the ground. If temp gets high enough, fuel flow drops to zero until the conditions in #1 are met with the throttle up > 80%. These temp effects are not seen on the normally aspirated version as far as I could tell.
