Why won't my truck start?

I have a 1992 Chevy K1500. Just recently it quit starting. It turns over, but seems like it isn't getting any fuel. I smelled around the carburetor and couldn't smell any gas. When I turned the key to the "on" I could hear the hum of the fuel pump. I sprayed a little starter fluid in the carb and it started right up. I was able to drive it home without any problems and it started up again right after I shut if off. I let the truck sit for a couple hours and tried to start it again. It did the same thing before and wouldn't start. I am not a mechanic by any means; any advice is appreciated. Is this a bad fuel pump or relay? Thanks!