Chrysler 1998 Voyager Service Manual page 1917

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DESCRIPTION AND OPERATION
CRANKCASE VENT FILTER . . . . . . . . . . . . . . . . 16
EVAPORATION CONTROL SYSTEM . . . . . . . . . 13
EVAPORATIVE (EVAP) CANISTER . . . . . . . . . . . 13
LEAK DETECTION PUMP . . . . . . . . . . . . . . . . . 14
POSITIVE CRANKCASE VENTILATION (PCV)
SYSTEMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
PRESSURE-VACUUM FILLER CAP . . . . . . . . . . 14
PROPORTIONAL PURGE SOLENOID . . . . . . . . . 13
DESCRIPTION AND OPERATION
EVAPORATION CONTROL SYSTEM
The evaporation control system prevents the emis-
sion of fuel tank vapors into the atmosphere. When
fuel evaporates in the fuel tank, the vapors pass
through vent hoses or tubes to a charcoal filled evap-
orative canister. The canister temporarily holds the
vapors. The Powertrain Control Module (PCM) allows
intake manifold vacuum to draw vapors into the com-
bustion chambers during certain operating condi-
tions.
All engines use a duty cycle purge system. The
PCM controls vapor flow by operating the duty cycle
EVAP purge solenoid. Refer to Duty Cycle EVAP
Purge Solenoid in this section.
NOTE: The evaporative system uses specially man-
ufactured hoses. If they need replacement, only use
fuel resistant hose.
ROLLOVER VALVE
All vehicles have a rollover valve. The valve also
prevents fuel flow through the fuel tank vent valve
hoses should the vehicle rollover. All vehicles pass a
360° rollover.
The charcoal filled evaporative canister stores the
vapors. The rollover valve is not a serviceable item.
EVAPORATIVE (EVAP) CANISTER
All vehicles use a sealed, maintenance free, evapo-
rative (charcoal) canister. The canister is attached to
the frame under the driver's seat (Fig. 1).
Fuel tank vapor vents into the canister. The canis-
ter temporarily holds the fuel vapors until intake
manifold vacuum draws them into the combustion
chamber. The canister proportional purge solenoid
EVAPORATIVE EMISSION CONTROLS
EMISSION CONTROL SYSTEMS
INDEX
page
ROLLOVER VALVE . . . . . . . . . . . . . . . . . . . . . . . 13
VEHICLE EMISSION CONTROL INFORMATION
LABEL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
DIAGNOSIS AND TESTING
LEAK DETECTION PUMP . . . . . . . . . . . . . . . . . 16
PCV VALVE TEST . . . . . . . . . . . . . . . . . . . . . . . 16
REMOVAL AND INSTALLATION
LEAK DETECTION PUMP REPLACEMENT . . . . 16
ROLLOVER VALVES . . . . . . . . . . . . . . . . . . . . . 17
allows the canister to be purged at predetermined
intervals and engine conditions.
Fig. 1 Evaporative Canister
PROPORTIONAL PURGE SOLENOID
All vehicles use a Proportional purge solenoid. The
solenoid regulates the rate of vapor flow from the
EVAP canister to the throttle body. The PCM oper-
ates the solenoid.
During the cold start warm-up period and the hot
start time delay, the PCM does not energize the sole-
noid. When de-energized, no vapors are purged. The
PCM de-energizes the solenoid during open loop oper-
ation.
25 - 13
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