A pressure regulating and pressure relief valve, has a valve body defining an inlet port, outlet port, valve seat and pressure relief opening. A pressure regulating plug is displaced during a first portion of a motion from an open position, which provides a continuous flow path from the inlet port to the outlet port, to a closed position in which the plug is closed against the valve seat to obstruct the continuous flow path. A spring biases the plug to the open position. An actuation surface is exposed to a pressure at the outlet port that displaces the plug against the spring bias toward the closed position. Further displacement of the plug beyond the closed position during a second portion of the motion that is beyond a range of the first portion of the motion, opens a relief flow path from the outlet port through the pressure release opening.