Bi-Fuel CNG Fuel System Metering Components

The primary components of the bi-fuel CNG fuel metering system are as follows:
^ High Pressure Regulator (HPR)
^ Low Pressure Regulator (LPR)
^ Fuel mixer
^ Idle solenoid
^ Fuel control solenoid

The CNG fuel system is controlled by the alternative fuels engine control module (AF ECM). The AF ECM receives input from various engine sensors in order to determine the amount of fuel necessary to maintain a precise air/fuel mixture across the entire engine operational range. The AF ECM then sends a command to the fuel control solenoid to meter the appropriate quantity of fuel. The fuel control solenoid meters the fuel flow by changing the pressure on the LPR diaphragm from atmosphere to vacuum. This system will also automatically sense and compensate for changes in altitude.