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Home >> Ford >> 1990 >> Bronco II RWD, Standard, M5OD-R1 >> Repair and Diagnosis >> Engine Performance >> Theory and Operation >> Engine Controls - Theory & Operation >> Evaporative Emission Control >> Fill Control/Vent System

Fill Control/Vent System

Fill limiting is accomplished through configuration of fill neck and/or internal vent lines within fill neck and tank. Vent system is designed to permit air space in 10-12 percent of tank, permitting room for thermal expansion.

On vehicles equipped with fuel/vapor return lines, vapor generated in fuel supply line is continuously vented back to fuel tank. Venting prevents engine surging from fuel enrichment and assists in hydrocarbon (HC) emission control.