Regenerative fuel pump having force-balanced impeller

A pump comprising:

• a pump housing comprising an internal pumping chamber and a fluid inlet to, and a fluid outlet from, the pumping chamber spaced arcuately apart about an axis;
• and
• a pumping element that is disposed within the housing for rotation about the axis and that has a body comprising a vaned periphery operable with respect to the pumping chamber to pump fluid from the inlet to the outlet when the pumping element is rotated, the pumping element body further having mutually parallel opposite faces circumferentially bounded by its vaned periphery;
• the pump housing comprising wall surfaces confronting the opposite faces of the pumping element body with close running clearance, the inlet being proximate one wall surface and the outlet being proximate the other wall surface;
• the pumping element body comprising a pattern of through-holes that have wall surfaces extending parallel to the pump axis between its faces with the one face that confronts the wall surface to which the inlet is proximate further comprising in association with each through-hole, a respective groove that adjoins and tails circumferentially away from the respective through-hole along an arc that is concentric with the pump axis in a sense opposite the sense in which the pumping element rotates to pump fluid from the inlet to the outlet, and that merges with the one face of the pumping element body at a location spaced circumferentially from the respective through-hole.