It has to have some other pump, or one built in to the high pressure pump. All diesels have some sort of pick up pump. The high pressure side does not have enough suction to pull fuel. I can't believe Cat made a dozer with gravity feed fuel tank. Could there be a pump in the tank? Talk to you your local Cat dealer or equipment repair shop. This doesn't sound like a line or tank problem. If the tank is lower than the pump and there is no pickup pump, how can it run on a hill? There is no kind of handle or pump on the filter housing? How do you bleed the injectors? Keep us posted, Joe
