Once a working procedure is found, stick to it ! Although I have flown with the Continental O470-11 (updraft carb) the book procedure calls for primer injection and that seems to cause hung starts quite often.(100LL,87 and Mogas)
I found out that using the throttle acceleration pump once or three times (depending on temp) starts the engine at first crank. Cranking must be immediately after the last throttle pumping action to prevent a carb intake fire. It helps if the ignition is also "ON" as I have seen many pilots forget to switch them on when cranking an engine ! That, and setting the mixture at full rich !
