Atmospheric pressure is a motive force that acts on fluids. But it takes a differential to cause movement. Whether it's the piston moving down the bore (creating a pressure less than atmospheric in the bore) or the diaphragm being pulled down by the pump lever (creating a pressure less than atmospheric in the pump chamber). It was stated by self-proclaimed engineers/experts that "There is NO suction going on in a mech fuel pump.". This is just NOT true. There may be a very slight measurable pressure less than atmospheric. That's because of very little restriction to flow by design. But it IS producing suction/vacuum. Pressure or vacuum is a measure of resistance to flow. The Doug Roe excerpts back up my claims. They don't contradict them. Read it again slowly.
|