A diaphragm controlled bypass valve includes a diaphragm valve portion and a needle valve portion. The diaphragm valve portion regulates pressurized gas supplied from a pump to determine whether or not to open or close a needle valve. The needle valve portion includes an inlet port, an outlet port and a flow pathway defined between the inlet and outlet ports. A needle pin is disposed within the flow pathway and is coupled to a diaphragm positioned within the diaphragm valve portion. When the diaphragm is displaced in response to changes in pressure, the needle valve pin is likewise displaced which opens and closes the flow pathway. A second flowpath disposed in the needle valve portion communicates with the inlet port to redirect the supply of pressurized gas to a relief port.