Jeep Cherokee 2000 Service Manual - page 1941
EVAPORATIVE EMISSION CONTROLS
TABLE OF CONTENTS
page
page
DESCRIPTION AND OPERATION
EVAPORATION CONTROL SYSTEM . . . . . . . . . . 23
ROLLOVER VALVE . . . . . . . . . . . . . . . . . . . . . . . 23
EVAP CANISTER . . . . . . . . . . . . . . . . . . . . . . . . . 24
DUTY CYCLE EVAP CANISTER PURGE
SOLENOID . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
LEAK DETECTION PUMP (LDP). . . . . . . . . . . . . . 24
CRANKCASE VENTILATION SYSTEM . . . . . . . . . 25
VEHICLE EMISSION CONTROL
INFORMATION (VECI) LABEL . . . . . . . . . . . . . . 26
DIAGNOSIS AND TESTING
VACUUM SCHEMATICS . . . . . . . . . . . . . . . . . . . . 26
LEAK DETECTION PUMP (LDP). . . . . . . . . . . . . . 27
CRANKCASE VENTILATION SYSTEM . . . . . . . . . 27
REMOVAL AND INSTALLATION
EVAP CANISTER . . . . . . . . . . . . . . . . . . . . . . . . . 27
DUTY CYCLE EVAP CANISTER PURGE
SOLENOID . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
ROLLOVER VALVE(S) . . . . . . . . . . . . . . . . . . . . . 27
LEAK DETECTION PUMP (LDP). . . . . . . . . . . . . . 28
SPECIFICATIONS
TORQUE CHART . . . . . . . . . . . . . . . . . . . . . . . . . 28
DESCRIPTION AND OPERATION
EVAPORATION CONTROL SYSTEM
OPERATION
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
Canister Purge Solenoid.
When equipped with certain emissions packages, a
Leak Detection Pump (LDP) will be used as part of
the evaporative system for OBD II requirements.
Also refer to Leak Detection Pump.
NOTE: The evaporative system uses specially man-
ufactured lines/hoses. If replacement becomes nec-
essary, only use fuel resistant hose.
ROLLOVER VALVE
DESCRIPTION
The fuel tank is equipped with a rollover valve.
The valve is located on the top of the fuel tank (Fig.
1).
OPERATION
The rollover valve will prevent fuel flow through
the fuel tank vent (EVAP) hoses in the event of an
accidental vehicle rollover. The EVAP canister draws
fuel vapors from the fuel tank through this valve.
Fig. 1 Rollover Valve Location
1 – ROLLOVER VALVE
2 – RETAINER CLAMP
3 – LOCKNUT
4 – FUEL PUMP MODULE
5 – FUEL FILTER/FUEL PRESSURE REGULATOR
6 – ALIGNMENT ARROW
7 – PIGTAIL HARNESS
8 – FUEL SUPPLY TUBE
9 – EVAP CANISTER VENT LINE
XJ
EMISSION CONTROL SYSTEMS
25 - 23