Fuel System Operation

This vehicles primary fuel source is Compressed Natural Gas (CNG). The AF ECM will only allow gasoline operation if one of the following conditions is present:
^ The CNG fuel tanks are empty as determined by the fuel tank pressure sensor.
^ The engine cranks for about 8 seconds and fails to start.
^ A system fault is detected by the AF ECM.
^ Every 100th start the AF ECM will allow the engine to start and run on gasoline. The AF ECM will switch-over to CNG operation during the first decel condition that occurs after a pre-determined amount of time has passed.