An example vane pump comprises a shaft driving a rotor. The rotor has a plurality of vane grooves, with a vane received in each of the plurality of vane grooves, and an under vane chamber for communicating a pressurized fluid into the grooves to bias the vanes radially outwardly of the rotor. A cam ring is positioned radially outwardly of the rotor. The cam ring is free to rotate with the rotor through friction from the vanes as the rotor rotates. An inlet delivers a fluid to be pumped into an inlet chamber, and an outlet receives the fluid pumped by the vane pump. An outlet for the fluid biasing the vanes communicates to a main outlet through a passage including a valve to increase the pressure of the fluid in the grooves.