A catheter blood pump includes a catheter, an expandable impeller housing, a drive cable, and a fixed-diameter impeller. The drive cable, which is operatively coupled to an extracorporeal motor, conveys torque that drives rotation of the impeller. The catheter and impeller housing are movable independently of one another to alter the relative axial positions of the catheter, impeller housing, and the fixed-diameter impeller. This arrangement maximizes the diameter of the catheter blood pump's fixed-diameter impeller.