Quote:

The factory pump has a check valve. It may not be sealing completly or the gas may be evaporating as posted above.



Evaporating from where? Inside the fuel filter? That's some magic evaporation if it can evaporate from inside a fuel filter. If your car is hard to start after sitting for a day, it's because the fuel is evaporating out of the carb and it takes some cranking to refill enough fuel into the bowl to fire it.