Abstract: A self-priming impeller type pump, particularly a centrifugal pump, is constructed so that the pump size and priming cycle time can be minimized. An impeller rotates about a generally horizontal axis within a housing having an inlet, with a diffuser portion of the housing adjacent the periphery of the impeller and defining a number of outlets. A front shroud of the impeller, adjacent the inlet, has external vanes which separate air from incoming liquid, and also facilitate recirculation of liquid from an outlet, to a recirculating liquid reservoir, and through a number of ports formed in the housing and extending generally parallel to the axis of rotation of the impeller. An air shield may be provided at the bottom of the housing to prevent air separated by diffuser peelers from passing to the recirculating ports. A reversing deflector is provided at the discharge from the topmost outlet to facilitate separation of air from liquid.