A pumping system includes s pump, a mechanical coupling device, and a cam shaft. The pump is effective to transfer fuel into an engine. The mechanical coupling device is coupled to the pump. The cam shaft couples to the mechanical coupling device. The cam shaft has an axis extending there through and rotates about the axis. The rotating of the cam shaft is effective to engage the mechanical coupling device and transfer a mechanical force created by the rotating to the mechanical coupling device. The mechanical coupling device is engaged to allow the mechanical force to be transferred to the fuel pump and activate the fuel pump when fuel is to be moved by the pump. The mechanical coupling device is disengaged to disallow the mechanical force from being transferred to the fuel pump and prevent the operation of the fuel pump.