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Fuel Evaporation System: Operation

With engine off, gasoline vapors are collected in the liquid-vapor separator. Liquid fuel is condensed and flows back to fuel tank. Vapors are routed to carbon canister where they are stored until engine is started. With engine running, vacuum opens the purge valve, allowing vapors to flow to intake manifold where they are burned. Liquid-vapor separator will compensate for fuel expansion of a filled fuel tank when temperatures fluctuate 80°F (27°C).

Fig 1: Fuel Evaporation System (318i Shown; 528e Similar)
G38518
Fig 2: Fuel Evaporation System (535i, 635CSi, 735i)
G37884
Fig 3: Fuel Evaporation System (325e)
G37883