a self - priming vane pump includes a cylindrical rotor disposed in a cavity in a housing including inlet and outlet ports . the rotor defines a plurality of axially extending slots which each receive one of a like plurality of vanes . a garter spring or similar resilient annulus is disposed within the rotor and provides a radially outwardly directed force on the vanes which maintains their contact with the cavity walls during pump start - up and rapidly self - primes the pump . the spring or annulus rests against a shoulder within the hollow rotor and is retained therein by a pressed in collar .