Stopped for gas then truck would not start

Truck normally starts right off. I had half a tank of gas, stopped and filled up truck cranked but wouldn't run, left truck at gas station came back next morning truck cranked right up drive to hotel. Truck started right up, went to a store truck won't start again. Cranks over but won't start. Sprayed carb cleaner truck runs until cleaner fuel is burned then dies. Waited hour or so, added heat to fuel tank. Attempted to start several times won't run. Tried one last time truck starts I drive home hour half ride. Get home turn truck off starts right back up. Next morning truck runs fine. Thought maybe the relay is going out but it has never died while running have not been able to locate where relay is at.