No Gas to the Carb When Engine Warms Up

The car stalls after driving for 15 min. When you step on the gas, no response. it won't restart, no fuel in the filter, no gas to the carb. if I let it sit over night, the filter is full. it starts right up and idles well, accelerates well, no problem on flat or hills.
My question is, why is it normal for there not to be gas in the filter? There's gas in the filter for about 15 min, then nothing. I guess that's why I didn't give more info about the stalling because I was concerned about the gas in the filter. Sorry for the confusion.