DESCRIPTION
The Evaporative Emission Control System (EECS), prevents raw fuel vapors from entering the atmosphere. It consists of a venting system which allows only vaporous fuel to be drawn into the system.
During engine operation, vapors are drawn through system vent lines and into intake manifold. When engine is off, fuel vapors are stored in vapor storage canister charcoal. Vapors are drawn into intake manifold when engine is running again.
OPERATION
Fuel vapors are vented through an orifice vapor separator assembly in top of fuel tank. Vapors then leave separator through a single vapor line, and continue to the carbon canister in engine compartment. The vapors are absorbed by carbon granules until they are purged from canister by carburetor/throttle body vacuum once engine is started.
FUEL FILLER CAP : Fuel filler cap has one-way vent. This prevents tank collapse, by allowing air to enter tank as fuel is consumed.
FUEL TANK : In most installations, fuel tank is constructed with dome in top. Fuel vapors rise and gather in this dome.
ORIFICE VALVE : On all vehicles, liquid fuel is prevented from entering vapor lines by restricted orifices. Orifices usually are a .050" (1.27 mm) orifice valve, located in emission control valve in fuel tank dome.
CARBON CANISTER : Carbon-filled canister acts as storage system for fuel vapors vented from fuel tank and carburetor/throttle body. Outlet of canister is connected to carburetor/throttle body bowl vent.
TESTING
Testing procedures are not available for the fuel evaporation system.
MAINTENANCE
No adjustments are required with this system. Replace air inlet filter (if equipped) in bottom of charcoal canister every 30,000 miles. Regular inspection should be made and defective components replaced as necessary.