EVAP System Schematic (NAS)

EVAP System Schematic (NAS)

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M17 0292

1 Vapour separator 2 EVAP canister 3 DMTL 4 Change-over valve 5 0.5 mm (0.020 in) reference orifice 6 Air pump and motor 7 Air filter 8 ECM 9 Throttle body

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10 Purge valve 11 Flap valve 12 Fuel tank 13 Roll over valve 14 ORVR valve 15 Two-way valve 16 Restrictor 17 Fuel filler cap 18 Filler tube

Two-way Valve The two-way valve limits the pressure and depression in the fuel tank and, during refuelling, induces automatic cutoff in the refuelling nozzle when the fuel in the tank reaches the full level. The two-way valve is installed in the vent pipe from the tank, next to the fuel pump assembly.

The two-way valve is a normally closed valve that opens, to release pressure from the fuel tank, at 18 to 50 mbar (0.26 and 0.73 lbf/in²). Air is allowed to flow back into the fuel tank, as the pressure in the tank decreases, through a non return valve within the body of the two-way valve. The nominal opening pressure of the non return valve is 1 mbar (0.015 lbf/in²).

During refuelling, if the fuel in the tank reaches the full level outward venting becomes restricted, which creates a back pressure in the filler tube and automatically closes the refuelling nozzle. On all except NAS vehicles, the restriction is caused by the fuel covering the outlet to the vent pipe connected to the top of the filler tube. On NAS vehicles, the restriction is caused by the fuel closing the ORVR valve.

Vapour Separator The vapour separator is installed at the front of the RH rear wheel arch, behind the wheel arch liner. The vapour separator prevents the charcoal in the EVAP canister being saturated with fuel, by separating any liquid from the vapour vented from the fuel tank. Separated fuel from the vapour separator drains back to the fuel tank through the vent pipe.