Abstract: An improved gaseous fuel delivery system and method (10) to improve performance of a gaseous fuel engine (30) by variably maintaining gaseous fuel pressure to the gaseous fuel engine (30). From a storage device (12), gaseous fuel flows to fuel pressure regulator (16) that variably and dynamically reduces the fuel pressure from the storage pressure and maintains the gaseous fuel pressure at the desired controlled supply pressure. Regulator controller (20) controls the fuel pressure regulator (16) in response to signal inputs (28, 34, 44, and 54) and maintain the gaseous fuel at the controlled supply pressure. Signal inputs (28, 34, 44, and 54) used by regulator controller (20) are derived from sensors such as fuel pressure sensor (24) an engine speed and/or intake manifold pressure sensor (34), fuel temperature sensor (42), and fuel composition sensor (52).