Fuel Evaporation System: Operation
When engine is stopped, fuel vapors from fuel tank flow through vapor line into charcoal canister where they are stored. When engine is running, fresh air drawn through charcoal canister creates a vacuum that pulls the stored fuel vapors into the engine.
A roll-over valve in the fuel evaporation line shuts off line if vehicle turns over. It is located in the line above fuel tank. The pressure valve is located in the left rear pillar and maintains a small pressure in the tank to reduce the amount of vapor the canister must store.
The special filler cap contains a pressure valve to let air into the tank if the vent lines become plugged. This prevents tank collapse or engine fuel starvation.