Quote: I just don't see why you think the mass of the fuel can be ignored.
it does not apply to this discussion, period
again...fluids exert force in all directions. the additional loading from the mass is distributed to the WALL of the container (hose, tubing etc.) not the bottom or in this case pump discharge.
look at it this way... you have two tanks both 30' tall full of water. one is ten feet in diameter the other is 150' in diameter. put a pressure gauge at the bottom of both tanks and the reading will be the same 12.99 PSI. what WILL be different is the wall thickness of the larger diameter tank will have to be greater than the smaller tank because the additional mass of the much greater quantity of water is exerted on the WALLS of the container not the bottom. the ten foot tank would probably hold up being made of sheet metal, try that with the big one and you'll have a flood.
