Walbro carbs require the engine's own internal pressure and vac pulses to operate the walbro internal pump. The tanks doen't require any pressurization from any source in gasoline set-ups. I suppose you could run muffler pressure but it won't help or hurt performance. The pump carbs havefuel deliverycovered.
You may be thinking of a YS type of pressurization and regulation fuel delivery set-up. Walbro carbs do not operate under such a set-up
I've heard that Walbro pumps are effective enough creating fuel draw (suction) from a tank that if a tank is not vented, the tank can be crushed like an aluminum beer can
ORIGINAL: Rudeboy
So the 15cc and 20cc engines do not run on crankcase pressure like stated on the website, but they run on muffler pressure?
Do you guys have any idea how much pressure the regulator system in the carb can take? Would it be possible to use a checkvalve and crankcase pressure? Or is that just too much for the regulator system?