ok i would bleed the fuel line with the key on. there is a bleed valve on the main fuel line somewhere near the engine. it has a screw on cap with a valve steam . Just press it wil a small screw driver with a cloth to soak up any fuel sprayed out. if there is pressure in the line. . If there is poor or no pressure. You could have a clogged fuel filter or by running the truck out of gas it burned up the fuel pump. As a rule of thumb never run a vehicle that has a electric fuel pump in the fuel tank lower that 1/4 of a tank of gas. The gas is used to keep the fuel pump cool it is submerged in.