All the carb needs is fuel in the bowl. It's pretty much like a toilet tank. Whether the toilet's tank is filled by a supply line with 100 psi or 20 psi or a bucket doesn't matter much.
well, that is not true
the carb is set up to withstand a certain inlet PSI, most times 8 PSI
the float can only withstand 8 PSI to close the inlet of fuel
if his line pressure is higher then that, the float, when rising to the top, will not be able to close the intake, and the bowls will flood
then fuel will drizzle into the throat of the carb and the car will run like crap
to stay with your toilet bowl analogy, your tank would overflow and water would pour all over your bathroom floor, next thing you know, the wife walks in, slips and falls, knocks her head on the toilet bowl (chipping it) and you're spending the rest of your life taking care of a woman on a respirator
