Abstract: A ventilation system (11) is provided to prevent the buildup of gaseous fuel within the vehicle upon degradation of the performance of the various parts within the fuel distribution system. The vehicle (10) has a combustible gas fuel source within the vehicle. The ventilation system includes a fuel line (28) coupling the engine (18) and the gas source. A vent line (30) is coupled to a vent. A pressure regulator (56) and pressure relief valve (60) are coupled between fuel line (28) and vent line. When either or both the pressure regulator (56) or relief valve (60) become inoperable, gaseous fuel is coupled to the vent line.

Abstract: A barrel throttle valve assembly (20) for use in an air intake system of an internal combustion engine. The barrel throttle valve assembly (20) includes a barrel (32) mounted within a housing (22), with the barrel (32) preferably including an upstream orifice (42), and idle notch (44) and a downstream orifice (46) for controlling the flow of idle air through the valve when the barrel (32) is in a substantially closed position, thus increasing the sensitivity of the valve at idle conditions. Also, preferably, a seal (48) and spring (54) is employed to reduce air leakage around the barrel (32).