a natural gas vehicle fuel delivery system regulates the pressure of lng which is vaporized and delivered to an engine . the system employs dual regulator valves responsive to the gas phase pressure of a storage tank to either directly couple vapor produced from a heat exchanger to an engine combustion system , or to divert that vapor through another heat exchanger contained within the tank itself . this additional heat exchanger maintains the pressure within the tank at the desired level despite heavy fuel demands of the engine . the system functions independent of liquid level in the storage tank . when multiple lng storage tanks are used , they are coupled in parallel so that they both produce gas and are concurrently regulated in the gas phase portion . a pressure initializing structure and process are also provided .