1958 Chevy 235, single 1 barrel Rochester with glass bowl fuel pump and glass fuel filter. The engine is freshly rebuilt. I rebuilt the carb myself.

If I pour gas in the carb, it starts right up, then dies as the gas is burned out of it. I can see gas in the fuel pump bowl, but very little gas in the fuel filter. I changed the fuel pump 3 times, still same problem. Can this be a problem with the carb, maybe vacuum leak? Where should I be checking?