Operation - Evaporation Control System

Fig 1: ORVR System Schematic (PZEV)

Courtesy of DAIMLERCHRYSLER CORP.

1 - FUEL TANK (PLASTIC)	11 - NATURAL VACUUM LEAD DETECTION (NVLD)
2 - FUEL FILLER TUBE	12 - LIQUID SEPARATOR (IF EQUIPPED)
3 - FUEL CAP (PRESSURE/RELIEF)	13 - ENGINE WIRING HARNESS TO NVLD
4 - FILL TUBE TO FUEL TANK CONNECTOR (ELASTOMERIC)	14 - VAPOR CANISTER
5 - TANK VENT/ROLLOVER VALVE(S)	15 - PURGE LINE
6 - VAPOR RECIRCULATION LINE	16 - PURGE DEVICE
7 - TANK VAPOR LINE	17 - WITHOUT NVLD
8 - VAPOR LINE TO CANISTER	18 - BREATHER ELEMENT
9 - CHECK VALVE (N/C)	19 - FLOW CONTROL ORIFICE
10 - CONTROL VALVE	20 - SERVICE PORT
	21 - WITH NVLD

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. See Fig 1.

All engines use a proportional purge solenoid system. The PCM controls vapor flow by operating the purge solenoid. Refer to VAPOR CANISTER .

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

NOTE: For more information on Onboard Refueling Vapor Recovery (ORVR), refer to ORVR .