the outlet passageway 82 is controlled in relation to the exposed area corresponding to the cover flow passageway 38 thereby providing a generally balanced force on opposing sides of the impeller 50 stated another way the impeller 50 is subject to a cover side force and a body side force which are designed to be approximately equal as used herein the terms about approximately generally and the like when used in relation to the forces and pressures on the impeller 50 encompass the fact that the actual pressure within the cover flow channel 38 may vary depending upon particular conditions e g pulsations or other pressure variations which in turn causes the opposing axial forces on the impeller 50 to vary which in turn causes the impeller 50 to float on the shaft 26 and is known in the art in our example the exposed area of the body side surface 53 of the impeller 50 is approximately one half of the exposed area on the cover side surface 52 of the impeller 50 in this way the impeller 50 is allowed to translate axially along the shaft 26 to accommodate pressure variations while at the same time maintaining an appropriate axial clearance of about 50 micron or less to ensure the ability of the pump to pressurize fuel to high pressure.