Dodge RAM 1500 1998 Owner's Manual page 2571

25 - 10 EVAPORATIVE EMISSIONS
EVAPORATIVE EMISSIONS
DESCRIPTION - EVAP SYSTEM
SPECIFICATIONS
TORQUE - EVAP SYSTEM . . . . . . . . . . . . . . . 11
CCV HOSE
DESCRIPTION - 8.0L V-10
OPERATION - 8.0L V-10
EVAP/PURGE SOLENOID
DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . 12
OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
REMOVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . 12
FUEL FILLER CAP
DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . 13
OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
REMOVAL
REMOVAL/INSTALLATION
LEAK DETECTION PUMP
DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . 13
OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
REMOVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . 16
EVAPORATIVE EMISSIONS
DESCRIPTION - EVAP 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 into the two charcoal
filled evaporative canisters. The canisters tempo-
rarily hold the vapors. The Powertrain Control Mod-
ule (PCM) allows intake manifold vacuum to draw
vapors into the combustion chambers during certain
operating conditions.
All gasoline powered engines use a duty cycle
purge system. The PCM controls vapor flow by oper-
ating the duty cycle EVAP purge solenoid. Refer to
Duty Cycle EVAP Canister Purge Solenoid for addi-
tional information.
EVAPORATIVE EMISSIONS
TABLE OF CONTENTS
page
. . . . . . . . . . . . 10
. . . . . . . . . . . . . . . . 12
. . . . . . . . . . . . . . . . . . 12
. . . . . . . . . . . . . . . 13
ORVR
DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . 17
OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
PCV VALVE
DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . 17
OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
DIAGNOSIS AND TESTING - PCV VALVE -
3.7L V-6/ 4.7L V-8 . . . . . . . . . . . . . . . . . . . . . . 20
REMOVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . 21
VACUUM LINES
DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . 22
VAPOR CANISTER
DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . 22
OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
REMOVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . 22
NATURAL VAC LEAK DETECTION ASSY
DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . 23
OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
REMOVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . 25
When equipped with certain emissions packages, a
Leak Detection Pump (LDP) will be used as part of
the evaporative system. This pump is used as a part
of OBD II requirements. Refer to Leak Detection
Pump for additional information. Other emissions
packages will use a Natural Vacuum Leak Detection
(NVLD) system in place of the LDP. Refer to NVLD
for additional information.
NOTE: The hoses used in this system are specially
manufactured. If replacement becomes necessary, it
is important to use only fuel resistant hose.
Certain EVAP system components can be found in
(Fig. 1).
DR
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