Porsche 928 GT1991, Руководство пользователя

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Fuel evaporation control
Fuel tank venting Vapor control system and storage Purge system
The expansion chamber and the safety valve
prevent fuel from escaping to the outside at
extreme high outside temperatures and
when the car is driven or parked at an incline
or in any other non-level position. The safety
valve works as a restrictor in the tank vent
line between the expansion chamber and
the carbon canister.
When the fuel tank is filled, vapors are col-
lected in the expansion chamber and filler-
tube by a vent line leading the vapors to the
activated carbon canister where they are
stored as long as the engine does not run.
During running of the engine, the vapors are
stored in the activated carbon canister as
long as the temperature controlled ON/OFF
valve is in the OFF-position.
The temperature controlled ON/OFF valve
stops purging of the canister during all other
running conditions of the engine if the cool-
ant temperature of the engine is below a de-
fined temperature.
Fuel vapors from the carbon canister will be
mixed with fresh air taken from the engine
compartment. This mixture will be directed
via two vacuum controlled valves to the air
intake system housing.
The temperature controlled ON/OFF valve
has the following functions:
To stop purging of the canister during idle
(the rich vapor flow from the canister would
influence the mixture characteristic).
To allow purging of the canister during all
other running conditions of the engine.
The vacuum controlled ON/OFF valve has
the function to control the purge flow (high
intake vacuum means low purge flow and
low intake vacuum means high purge flow).
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