The high pressure regulator (HPR) is supplied with fuel from the CNG fuel tank. The HPR reduces CNG fuel pressure from 24 820 kPa (3,600 psi) to approximately 1 172 kPa (170 psi). The HPR is mounted on the driver's side at the base of the CNG tank frame assembly in the trunk compartment. In order to prevent freezing during pressure reduction, the HPR is heated with engine coolant supplied through hoses. The HPR has an internal 40 micron filter that requires servicing at specified intervals. Refer to Periodic Maintenance Inspection in Maintenance and Lubrication for service intervals.

The low pressure lock-off (LPL) solenoid is an electrically operated valve that allows gaseous fuel to flow to the low pressure regulator (LPR). The LPL solenoid is located in-line between the HPR and the LPR. The AF ECU controls the LPL solenoid. When the solenoid is energized, the valve opens allowing fuel to flow to the LPR. The LPL is energized only when the engine is cranking or running. Anytime the engine is stopped (ignition ON or OFF), the LPL closes to shut off the fuel supply.

When the lock pressure lock-off (LPL) is opened, the low pressure regulator (LPR) receives CNG at the inlet pressure regulated by the HPR. The LPR is a two-stage pressure regulator which reduces CNG fuel pressure from 1 172 kPa (170 psi) to approximately 1.5 kPa (0.21 psi). The LPR is located between the LPL and the gas mass sensor/mixture control valve (GMS/MCV). The LPR has two 1/8 inch NPT test ports. One port is for monitoring primary stage pressure while the other port is for monitoring secondary stage pressure.

The gas mass sensor/mixture control valve (GMS/MCV) combines a hot wire anemometer and a magnetic rotary valve. The GMS/MCV is located between the LPR and the gas distribution adapter (GDA). The GMS measures the mass fuel flow and outputs a frequency to the AF ECU. The AF ECU processes this signal and determines the amount of fuel entering the engine. Comparing this with the optimum fuel flow rate required to obtain stoichiometry and using feedback from various engine sensors, the AF ECU modulates the MCV in order to maintain a stoichiometric air/fuel ratio.

The gas distribution adapter (GDA) replaces the air inlet duct. The GDA is mounted to the throttle body. The GDA contains the gas ring, which has machined slots in order to introduce the CNG into the intake air stream.

The fuel hoses are low-pressure, wire reinforced hoses. One fuel hose delivers CNG from the LPR to the GMS/MCV and the other fuel hose delivers CNG from the GMS/MCV to the GDA.