Evaporative Emission Control System

DESCRIPTION
The evaporative system reduces hydrocarbon emissions by trapping fuel tank vapors until they can be burned as part of the incoming fuel charge. Evaporating fuel is stored in a charcoal canister until it can be flushed into the intake manifold.

The evaporative control system is made up of the following components:

1. Fuel tank, fuel/vapor separator and fuel tank pressure sensor.
2. Canister and canister close valve.
3. Purge control valve.

In normal operation, the purge control valve opens and closes depending on throttle angle and intake manifold vacuum. When it opens fuel vapors are flushed from the canister and drawn into the intake manifold. To avoid a vacuum build-up in the canister, the canister close valve in normally held open to allow fresh air to replace the vapors drawn into the intake manifold.