Fuel Evaporation System: Operation
Fuel vapor from the sealed fuel tank is stored in the charcoal canister when the engine is stopped or idling. As the throttle valve opens and engine speed increases, vacuum opens the purge control valve and fuel vapors are drawn from canister into the intake manifold.
On Pulsar NX and Sentra models, the control unit closes the canister control solenoid valve to prevent any purging of the canister by preventing the opening of the purge valve when coolant temperature is less than 140°F (60°C), as relayed to the control unit from the thermal vacuum valve.
On all other models, when the purge valve is closed, a small amount of purge air flows into intake manifold through the constant purge orifice.