Fuel Flow Meter: Description and Operation

The GMS/MCV combines a hot wire type anemometer (GMS) and a Magnetic Rotary Valve (MCV) into one non-serviceable unit. The GMS/MCV is mounted in the low pressure hose between the Low Pressure Regulator (LPR) and the Gas Distribution Adaptor (GDA). The GMS measures the mass fuel flow and outputs a frequency signal to the Alternative Fuels Engine Control Unit (AF ECU). The AF ECU process this signal to determine the amount of fuel entering the engine. The AF ECU compares the GMS information as well as the information of other engine sensors and determines an optimum fuel flow rate to maintain a stoichiometric air/fuel ratio of 16.5 to 1. In order to change the fuel mixture rich or lean, the AF ECU modulates the MCV. The MCV will then allow less or more fuel into the engine.