A vane pump includes a first cam ring and a second cam ring, a first rotor positioned in the first cam ring and a second rotor positioned in the second cam ring, and a shaft. The first rotor is engaged with the shaft so that the first rotor rotates relative to the first cam ring about an axis extending through the shaft, and the second rotor selectively engages with the shaft so that the second rotor selectively rotates relative to the second cam ring about the axis. A piston positioned in the shaft translates within the shaft between a first position and a second position. When in the first position, the shaft engages with the second rotor so that the second rotor rotates relative to the second cam ring about the axis, and when in the second position, the shaft disengages with the second rotor so that the second rotor does not rotate relative to the second cam ring.