When I learnt to fly we had some old knackered PA28's that were allowed to go 100 hours between checks by the authority as a concession.
If they had too much fuel in the system, we used to start them by fully opening the throttle, fully closing the mixture and then swapping the levers round once it fired.
This work every time as long as you managed the swap fast enough, and if not, a normal start worked after this procedure.
I have no idea if that's what we were supposed to be doing, but most of the instructors were ex-military test pilots!!