Need more gas??

[BB72CHEVKT]

I installed my refurb stock tank back in the truck. After instaling the tank I added about 1/2 gallon of gas and drove around the block. Coming back up the hill it died. I figured there was not enough gas in the tank for it to pick up. Got 2 more gallons added to the tank and took off for another spin. When I went down a hill the coming up the other side it died again. I got it back to the house and since the battery was dead I left it alone for the night. Do you think there is still not sufficent gas in the tank for it to go down and back up a fairly steep hill? Please also take note that this truck had been sitting for 15 years. I did change the fuel filter and all rubber fuel lines as well.