same thing happened to me, until one night i was changing my air cleaner and noticed a squirting sound coming from the intake, i looked down the carb and every few seconds some gas would squirt out of and down the intake, if i let it sit for a week the thing would never start well im guessing all the fuel would leak out of the bowls and evaporate i took the car off cleaned it and now its fine. but i would first check out the pump like Denny said hes usually pretty on target. and plus he has been working on cars longer than i have been alive haha. but if all else fails clean the carb with carb cleaner because carb cleaner fixes EVERYTHING!!!!!!!!