I have had the same problem with my P60 usually on the first start of the day. After that it usually starts without a hitch. I put it down to a sticky fuel pump as it is relatively new. I fly in warm temperatures...up to 30 degrees C and always make sure that my gas is filled 1/2 hour before I fly to allow the cannister and its contents to reach ambient temp so I don't think temperature is the issue here. I tested my fuel pump outside the model but I would assume that the ECU would shut down the engine if the rise in RPM during start is inconsistent with the supplied pump voltage. The supplied pump voltage might not tranlsate into proportional fuel flow if the pump is sticky though, and this is hard to judge without some accurate standards and measurements to work with.