System Description

EVAPORATION CONTROL SYSTEM
The evaporation control system prevents the emission of fuel tank vapors into the atmosphere. When fuel evaporates in the fuel tank, the vapors pass through vent hoses or tubes to an activated carbon filled evaporative canister. The canister temporarily holds the vapors. The Powertrain Control Module (PCM) allows intake manifold vacuum to draw vapors into the combustion chambers during certain operating conditions.

All engines use a duty cycle purge system. The PCM controls vapor flow by operating the duty cycle EVAP purge solenoid (Refer to EMISSIONS CONTROL/EVAPORATIVE EMISSIONS/EVAP/PURGE SOLENOID - OPERATION).

NOTE: The evaporative system uses specially manufactured hoses. they need replacement, only use fuel resistant hose. Also the hoses must be able to pass an Ozone compliance test.

CCV SYSTEM
The 8.0 L V-10 engine is equipped with a Crankcase Ventilation (CCV) system. The CCV system performs the same function as a conventional PCV system, but use a fixed orifice instead of vacuum controlled valve (PCV valve).

Fig. 1 Fixed Orifice Fitting:

It meters the amount of crankcase vapors drawn out of the engine. The fixed orifice fitting is grey in color.

When the engine is operating, fresh air enters the engine and mixes with crankcase vapors. Manifold vacuum draws the vapor/air mixture through the fixed orifice and into the intake manifold. The vapors are then consumed during engine combustion.