A pump used in vehicle controlled braking systems provides a reverse direction of flow through a cylinder bore of the pump and utilizes an inlet check valve located outside of the piston at the end of the cylinder bore opposite the piston, in conjunction with an outlet check valve located in an outlet extending through a sidewall of the cylinder bore of the pump. The inlet check valve is assembled and tested as a module prior to being installed in the pump. A fluid reservoir, having a movable wall, is connected to the inlet to facilitate priming the pump module. The piston is driven by a self-supporting drive apparatus with an eccentric element affixed to a stub shaft, or by other forms of a drive apparatus having an eccentric element fixed to a motor drive shaft.