Porsche 911 Carrera - Manual (Page 251)

Fuel Evaporation Control
Fuel tank venting
The evaporation chamber and the carbon canister
prevent fuel from escaping to the atmosphere at
extreme high outside temperatures, when driving
abruptly around curves and when the car is parked
at an incline or in any other nonlevel position.
Vapor control system and storage
When the fuel tank is filled, vapors are collected
in the evaporation chamber by a vent line leading
the vapors to the carbon canister where they are
stored as long as the engine does not run.
Purge system
When the engine is running, the fuel vapors from
the canister will be mixed with fresh air from the
ambient air of the canister. This mixture will be
directed to the intake air housing by the tank vent
line, mixed with the intake air and burned during
normal combustion.
Maintenance, Car Care
249