Fuel tank venting

A fuel tank filler neck assembly, said assembly comprising a filler neck adapted for connection to a fuel tank, a plate that pivots between a position restricting said filler neck and a position permitting introduction of fuel through said filler neck, a vent housing having a vapor inlet fitting adapted for connection to said fuel tank separately from said filler neck, said housing also having a vapor outlet fitting connected to said vapor inlet fitting through a vent orifice, a pressure control orifice, and a vacuum relief orifice, a diaphragm vent valve isolating said vent housing from said filler neck and controlling flow through said vent orifice, an actuating arm pivoted with said restrictor plate and adapted to engage said vent valve across said vent orifice when said restrictor plate restricts said filler neck, said actuating arm permitting said vent valve to allow vapor flow from said vapor inlet fitting through said vent orifice to said vapor outlet fitting when said restrictor plate permits introduction of fuel through said filler neck, a diaphragm pressure control valve controlling flow through said pressure control orifice, and a vacuum relief valve controlling flow through said vacuum relief orifice.