2002 JEEP LIBERTY Valve cover

(8) Pressure should not fall below30 psi for five
minutes.
(9) If pressure falls below 30 psi, it must be deter-
mined if a fuel injector, the check valve within the
fuel pump module, or a fuel tube/line is leaking.
(10) Again, start engine and bring to normal oper-
ating temperature.
(11) Shut engine off.
(12)Testing for fuel injector or fuel rail leak-
age:Clamp off the rubber hose portion of Adaptor
Tool between the fuel rail and the test port ªTº on
Adapter Tool. If pressure now holds at or above 30
psi, a fuel injector or the fuel rail is leaking.
(13)Testing for fuel pump check valve, filter,
regulator check valve or fuel tube/line leakage:
Clamp off the rubber hose portion of Adaptor Tool
between the vehicle fuel line and test port ªTº on
Adapter Tool. If pressure now holds at or above 30
psi, a leak may be found at a fuel tube/line. If no
leaks are found at fuel tubes or lines, one of the
check valves in either the electric fuel pump, fuel fil-
ter or fuel pressure regulator may be leaking.
Note: A quick loss of pressure usually indicates a
defective check valve in the pressure regulator. A
slow loss of pressure usually indicates a defective
check valve in the bottom of the fuel pump module.
The check valves are not serviced separately. Also,
the electric fuel pump is not serviced separately.
STANDARD PROCEDURE - FUEL SYSTEM
PRESSURE RELEASE
Use following procedure if the fuel injector
rail is, or is not equipped with a fuel pressure
test port.
(1) Remove fuel fill cap.
(2) Remove fuel pump relay from Power Distribu-
tion Center (PDC). For location of relay, refer to label
on underside of PDC cover.(3) Start and run engine until it stalls.
(4) Attempt restarting engine until it will no
longer run.
(5) Turn ignition key to OFF position.
CAUTION: Steps 1, 2, 3 and 4 must be performed to
relieve high pressure fuel from within fuel rail. Do
not attempt to use following steps to relieve this
pressure as excessive fuel will be forced into a cyl-
inder chamber.
(6) Unplug connector from any fuel injector.
(7) Attach one end of a jumper wire with alligator
clips (18 gauge or smaller) to either injector terminal.
(8) Connect other end of jumper wire to positive
side of battery.
(9) Connect one end of a second jumper wire to
remaining injector terminal.
CAUTION: Powering an injector for more than a few
seconds will permanently damage the injector.
(10) Momentarily touch other end of jumper wire
to negative terminal of battery for no more than a
few seconds.
(11) Place a rag or towel below fuel line quick-con-
nect fitting at fuel rail.
(12) Disconnect quick-connect fitting at fuel rail.
Refer to Quick-Connect Fittings.
(13) Return fuel pump relay to PDC.
(14) One or more Diagnostic Trouble Codes (DTC's)
may have been stored in PCM memory due to fuel
pump relay removal. The DRBtscan tool must be
used to erase a DTC.
14 - 4 FUEL DELIVERYKJ
FUEL DELIVERY (Continued)

of the firing of the fuel injectors. It isnot usedas a
fuel pressure regulator. The fuel pressure regulator is
not mountedto the fuel rail on any engine. It is
located on the fuel tank mounted fuel pump module.
Refer to Fuel Pressure Regulator for additional infor-
mation.
The fuel rail is not repairable.
A quick-connect fitting with a safety latch is used
to attach the fuel line to the fuel rail.
3.7L
High pressure fuel from the fuel pump is routed to
the fuel rail. The fuel rail then supplies the neces-
sary fuel to each individual fuel injector.
A quick-connect fitting with a safety latch is used
to attach the fuel line to the fuel rail.
The fuel rail is not repairable.
REMOVAL
2.4L
WARNING: THE FUEL SYSTEM IS UNDER CON-
STANT PRESSURE EVEN WITH ENGINE OFF.
BEFORE SERVICING FUEL RAIL, FUEL SYSTEM
PRESSURE MUST BE RELEASED.
The fuel rail can be removed without removing the
intake manifold if the following procedures are fol-
lowed.(1) Remove fuel tank filler tube cap.
(2) Perform Fuel System Pressure Release Proce-
dure.
(3) Remove negative battery cable at battery.
(4) Remove air duct at throttle body.
(5) Disconnect fuel line latch clip and fuel line at
fuel rail. A special tool will be necessary for fuel line
disconnection. Refer to Quick-Connect Fittings.
(6) Remove necessary vacuum lines at throttle
body.
(7) Drain engine coolant and remove thermostat
and thermostat housing.
(8) Remove PCV hose and valve at valve cover.
(9) Remove 3 upper intake manifold mounting
bolts (Fig. 35), but only loosen 2 lower bolts about 2
turns.
(10) Disconnect 2 main engine harness connectors
at rear of intake manifold (Fig. 34).
(11) Disconnect 2 injection wiring harness clips at
harness mounting bracket (Fig. 35).
(12) Disconnect electrical connectors at all 4 fuel
injectors. To remove connector refer to (Fig. 37). Push
red colored slider away from injector (1). While push-
ing slider, depress tab (2) and remove connector (3)
from injector. The factory fuel injection wiring har-
ness is numerically tagged (INJ 1, INJ 2, etc.) for
injector position identification. If harness is not
tagged, note wiring location before removal.
(13) Remove 2 injection rail mounting bolts (Fig.
31).
Fig. 34 MAP SENSOR LOCATION-2.4L
1 - REAR OF INTAKE MANIFOLD
2 - MAP SENSOR
3 - ALIGNMENT PIN
4 - MOUNTING BOLT (TORX)
5 - ELECTRICAL CONNECTOR
6 - MAIN ENGINE HARNESS CONNECTORS
Fig. 35 FUEL RAIL MOUNTING-2.4L
1 - FUEL RAIL
2 - INJECTION HARNESS CLIPS
3 - LOWER MOUNTING HOLES
4 - UPPER MOUNTING HOLES
5 - INTAKE MANIFOLD
14 - 22 FUEL DELIVERYKJ
FUEL RAIL (Continued)

(14) Remove the two roll down bracket bolts at the
left cowl side panel. (Fig. 6)
(15) Remove the ground strap bolt and disconnect
the restraint module electrical connector. (Fig. 3)
(16) Remove the glove box. (Refer to 23 - BODY/
INSTRUMENT PANEL/GLOVE BOX - REMOVAL)
(17) Remove the two HVAC mounting bolts behind
the center trim. (Fig. 3)
(18) Remove the passenger side trim bezel. (Refer
to 23 - BODY/INSTRUMENT PANEL/IP PASSEN-
GER SIDE BEZEL - REMOVAL)(19) Remove the HVAC mounting bolt above the
glove box striker. (Fig. 4)
(20) Remove the HVAC bolt at the lower outside
corner of the glove box opening. (Fig. 5)
(21) Remove the passenger side cowl trim cover.
(Refer to 23 - BODY/INTERIOR/COWL TRIM
COVER - REMOVAL)
(22) Disconnect the blower resistor electrical con-
nector. (Fig. 5)
(23) Remove the two roll down bracket bolts at the
right cowl side panel.
Fig. 2 PEDAL SUPPORT BRACKET
1 - PEDAL SUPPORT BRACKET
2 - BOLTS
3 - BOLTS
4 - ELECTRICAL CONNECTOR
Fig. 3 HVAC BOLTS
1 - RESTRAINT MODULE
2 - HVAC BOLTS
3 - RADIO WIRE HARNESS
Fig. 4 HVAC UPPER BOLT
1 - BOLT
2 - GLOVE BOX STRIKER
3 - HVAC UNIT
Fig. 5 HVAC CONNECTIONS
1 - GLOVE BOX STRIKER
2 - BLOWER RESISTOR
3 - VACUUM CHECK VALVE
4 - BOLT
23 - 150 INSTRUMENT PANELKJ
INSTRUMENT PANEL ASSEMBLY (Continued)

PLUMBING
TABLE OF CONTENTS
page page
PLUMBING
DESCRIPTION - REFRIGERANT LINE.......38
WARNING
SERVICE WARNINGS..................39
CAUTION
SERVICE CAUTIONS..................39
CAUTION - REFRIGERANT HOSES/LINES/
TUBES PRECAUTIONS.................40
STANDARD PROCEDURE
STANDARD PROCEDURE - REFRIGERANT
SYSTEM SERVICE EQUIPMENT..........40
STANDARD PROCEDURE - REFRIGERANT
RECOVERY..........................41
STANDARD PROCEDURE - REFRIGERANT
SYSTEM EVACUATE...................41
STANDARD PROCEDURE - REFRIGERANT
SYSTEM CHARGE.....................41
SPECIFICATIONS - CHARGE CAPACITY.....42
A/C COMPRESSOR
DESCRIPTION
DESCRIPTION........................42
DESCRIPTION - HIGH PRESSURE RELIEF
VALVE..............................42
OPERATION
OPERATION.........................42
OPERATION - HIGH PRESSURE RELIEF
VALVE..............................42
DIAGNOSIS AND TESTING - A/C
COMPRESSOR NOISE.................42
REMOVAL.............................43
INSTALLATION.........................44
A/C CONDENSER
DESCRIPTION.........................45
OPERATION...........................45
REMOVAL.............................45
INSTALLATION.........................46
A/C DISCHARGE LINE
REMOVAL.............................46INSTALLATION.........................47
A/C LIQUID LINE
REMOVAL.............................47
INSTALLATION.........................47
A/C SUCTION LINE
REMOVAL.............................48
INSTALLATION.........................49
A/C EVAPORATOR
DESCRIPTION.........................49
OPERATION...........................49
REMOVAL.............................49
INSTALLATION.........................49
A/C ORIFICE TUBE
DESCRIPTION.........................50
OPERATION...........................50
REMOVAL.............................50
INSTALLATION.........................50
ACCUMULATOR
DESCRIPTION.........................51
OPERATION...........................51
REMOVAL.............................51
INSTALLATION.........................51
HEATER CORE
DESCRIPTION.........................52
OPERATION...........................52
REMOVAL.............................52
INSTALLATION.........................53
REFRIGERANT
DESCRIPTION.........................53
OPERATION...........................53
REFRIGERANT OIL
DESCRIPTION.........................53
OPERATION...........................54
STANDARD PROCEDURE - REFRIGERANT
OIL LEVEL...........................54
PLUMBING
DESCRIPTION - REFRIGERANT LINE
The refrigerant lines and hoses are used to carry
the refrigerant between the various air conditioning
system components. A barrier hose design with a
nylon tube, which is sandwiched between rubber lay-
ers, is used for the R-134a air conditioning system on
this vehicle. This nylon tube helps to further containthe R-134a refrigerant, which has a smaller molecu-
lar structure than R-12 refrigerant. The ends of the
refrigerant hoses are made from lightweight alumi-
num or steel, and commonly use braze-less fittings.
Any kinks or sharp bends in the refrigerant plumb-
ing will reduce the capacity of the entire air condi-
tioning system. Kinks and sharp bends reduce the
flow of refrigerant in the system. A good rule for the
flexible hose refrigerant lines is to keep the radius of
all bends at least ten times the diameter of the hose.
24 - 38 PLUMBINGKJ

CAUTION - REFRIGERANT HOSES/LINES/
TUBES PRECAUTIONS
Kinks or sharp bends in the refrigerant plumbing will
reduce the capacity of the entire system. High pressures
are produced in the system when it is operating.
Extreme care must be exercised to make sure that all
refrigerant system connections are pressure tight.
A good rule for the flexible hose refrigerant lines is
to keep the radius of all bends at least ten times the
diameter of the hose. Sharp bends will reduce the
flow of refrigerant. The flexible hose lines should be
routed so they are at least 80 millimeters (3 inches)
from the exhaust manifold. It is a good practice to
inspect all flexible refrigerant system hose lines at
least once a year to make sure they are in good con-
dition and properly routed.
There are two types of refrigerant fittings:
²
All fittings with O-rings need to be coated with
refrigerant oil before installation. Use only O-rings that
are the correct size and approved for use with R-134a
refrigerant. Failure to do so may result in a leak.
²Unified plumbing connections with gaskets can-
not be serviced with O-rings. The gaskets are not
reusable and new gaskets do not require lubrication
before installing.
Using the proper tools when making a refrigerant
plumbing connection is very important. Improper
tools or improper use of the tools can damage the
refrigerant fittings. Always use two wrenches when
loosening or tightening tube fittings. Use one wrench
to hold one side of the connection stationary, while
loosening or tightening the other side of the connec-
tion with a second wrench.
The refrigerant must be recovered completely from
the system before opening any fitting or connection.
Open the fittings with caution, even after the refrig-
erant has been recovered. If any pressure is noticed
as a fitting is loosened, tighten the fitting and
recover the refrigerant from the system again.
Do not discharge refrigerant into the atmosphere.
Use an R-134a refrigerant recovery/recycling device
that meets SAE Standard J2210.
The refrigerant system will remain chemically sta-
ble as long as pure, moisture-free R-134a refrigerant
and refrigerant oil is used. Dirt, moisture, or air can
upset this chemical stability. Operational troubles or
serious damage can occur if foreign material is
present in the refrigerant system.
When it is necessary to open the refrigerant sys-
tem, have everything needed to service the system
ready. The refrigerant system should not be left open
to the atmosphere any longer than necessary. Cap or
plug all lines and fittings as soon as they are opened
to prevent the entrance of dirt and moisture. All lines
and components in parts stock should be capped or
sealed until they are to be installed.All tools, including the refrigerant recycling equip-
ment, the manifold gauge set, and test hoses should
be kept clean and dry. All tools and equipment must
be designed for R-134a refrigerant.
STANDARD PROCEDURE
STANDARD PROCEDURE - REFRIGERANT
SYSTEM SERVICE EQUIPMENT
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS SECTION BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - WARNING) (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - CAUTION)
When servicing the air conditioning system, a
R-134a refrigerant recovery/recycling/charging sta-
tion that meets SAE Standard J2210 must be used.
Contact an automotive service equipment supplier for
refrigerant recovery/recycling/charging equipment.
Refer to the operating instructions supplied by the
equipment manufacturer for proper care and use of
this equipment.
A manifold gauge set may be needed with some
recovery/recycling/charging equipment (Fig. 1). The
service hoses on the gauge set being used should
have manual (turn wheel), or automatic back-flow
valves at the service port connector ends. This will
prevent refrigerant from being released into the
atmosphere.
MANIFOLD GAUGE SET CONNECTIONS
CAUTION: Do not use an R-12 manifold gauge set
on an R-134a system. The refrigerants are not com-
patible and system damage will result.
LOW PRESSURE GAUGE HOSE The low pressure
hose (Blue with Black stripe) attaches to the suction
service port. This port is located on the suction line
between the accumulator outlet and the compressor.
HIGH PRESSURE GAUGE HOSE The high pres-
sure hose (Red with Black stripe) attaches to the dis-
charge service port. This port is located on the
discharge line between the compressor and the con-
denser inlet.
RECOVERY/RECYCLING/EVACUATION/CHARG-
ING HOSE The center manifold hose (Yellow, or
White, with Black stripe) is used to recover, evacu-
ate, and charge the refrigerant system. When the low
or high pressure valves on the manifold gauge set
are opened, the refrigerant in the system will escape
through this hose.
24 - 40 PLUMBINGKJ
PLUMBING (Continued)

STANDARD PROCEDURE - REFRIGERANT
RECOVERY
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS SECTION BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - WARNING) (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - CAUTION)
A R-134a refrigerant recovery/recycling/charging
station that meets SAE Standard J2210 must be
used to recover the refrigerant from an R-134a refrig-
erant system. Refer to the operating instructions sup-
plied by the equipment manufacturer for the proper
care and use of this equipment.
STANDARD PROCEDURE - REFRIGERANT
SYSTEM EVACUATE
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS SECTION BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/PLUMBING - WARNING) (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - CAUTION)
If the refrigerant system has been open to the
atmosphere, it must be evacuated before the system
can be charged. If moisture and air enters the system
and becomes mixed with the refrigerant, the com-
pressor head pressure will rise above acceptable
operating levels. This will reduce the performance of
the air conditioner and damage the compressor.
Evacuating the refrigerant system will remove the
air and boil the moisture out of the system at near
room temperature. To evacuate the refrigerant sys-
tem, use the following procedure:
(1) Connect a R-134a refrigerant recovery/recy-
cling/charging station that meets SAE Standard
J2210 and a manifold gauge set to the refrigerant
system of the vehicle.
(2) Open the low and high side valves and start
the charging station vacuum pump. When the suc-
tion gauge reads 88 kPa (26 in. Hg.) vacuum or
greater, close all of the valves and turn off the vac-
uum pump.
(a) If the refrigerant system fails to reach the
specified vacuum, the system has a leak that must
be corrected. (Refer to 24 - HEATING & AIR CON-
DITIONING/PLUMBING - DIAGNOSIS AND
TESTING - REFRIGERANT SYSTEM LEAKS)
(b) If the refrigerant system maintains the spec-
ified vacuum for five minutes, restart the vacuum
pump, open the suction and discharge valves and
evacuate the system for an additional ten minutes.
(3) Close all of the valves, and turn off the charg-
ing station vacuum pump.
(4) The refrigerant system is now ready to be
charged with R-134a refrigerant. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM CHARGE)
STANDARD PROCEDURE - REFRIGERANT
SYSTEM CHARGE
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS SECTION BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - WARNING) (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - CAUTION)
After the refrigerant system has been tested for
leaks and evacuated, a refrigerant charge can be
injected into the system. (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - SPECIFICA-
TIONS - CHARGE CAPACITY)
A R-134a refrigerant recovery/recycling/charging
station that meets SAE Standard J2210 must be
Fig. 1 MANIFOLD GAUGE SET - TYPICAL
1 - HIGH PRESSURE GAUGE
2 - VALVE
3 - VACUUM/REFRIGERANT HOSE (YELLOW W/ BLACK
STRIPE)
4 - HIGH PRESSURE HOSE (RED W/ BLACK STRIPE)
5 - LOW PRESSURE HOSE (BLUE W/ BLACK STRIPE)
6 - VALVE
7 - LOW PRESSURE GAUGE
KJPLUMBING 24 - 41
PLUMBING (Continued)

(3) To duplicate a high-ambient temperature condi-
tion (high head pressure), restrict the air flow
through the condenser. Install a manifold gauge set
to be certain that the discharge pressure does not
exceed 2760 kPa (400 psi).
(4) Check the refrigerant system plumbing for
incorrect routing, rubbing or interference, which can
cause unusual noises. Also check the refrigerant lines
for kinks or sharp bends that will restrict refrigerant
flow, which can cause noises. (Refer to 24 - HEAT-
ING & AIR CONDITIONING/PLUMBING - CAU-
TION)
(5) If the noise is from opening and closing of the
high pressure relief valve, evacuate and recharge the
refrigerant system. (Refer to 24 - HEATING & AIR
CONDITIONING/PLUMBING - STANDARD PRO-
CEDURE - REFRIGERANT SYSTEM EVACUATE)
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - STANDARD PROCEDURE - REFRIG-
ERANT SYSTEM CHARGE) If the high pressure
relief valve still does not seat properly, replace the
compressor.
(6) If the noise is from liquid slugging on the suc-
tion line, replace the accumulator. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING/AC-
CUMULATOR - REMOVAL) Check the refrigerant oil
level and the refrigerant system charge. (Refer to 24
- HEATING & AIR CONDITIONING/PLUMBING/
REFRIGERANT OIL - STANDARD PROCEDURE)
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - SPECIFICATIONS - CHARGE
CAPACITY) If the liquid slugging condition continues
following accumulator replacement, replace the com-
pressor. (Refer to 24 - HEATING & AIR CONDI-
TIONING/PLUMBING/A/C COMPRESSOR -
REMOVAL)
(7) If the noise continues, replace the compressor
and repeat Step 1.
REMOVAL
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS SECTION BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - WARNING) (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - CAUTION)
The compressor may be removed and repositioned
without disconnecting the refrigerant lines or dis-
charging the refrigerant system. Discharging is not
necessary if servicing the compressor clutch or clutch
coil, the engine, the cylinder head, or the generator.
(1) Recover the refrigerant from the refrigerant
system. (Refer to 24 - HEATING & AIR CONDI-
TIONING/PLUMBING - STANDARD PROCEDURE -
REFRIGERANT RECOVERY)(2) Disconnect and isolate the battery negative
cable.
(3) Remove the serpentine drive belt(Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
REMOVAL).
(4) Unplug the compressor clutch coil wire harness
connector.
(5) Remove the suction and discharge refrigerant
line manifold from the compressor. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING/
SUCTION LINE - REMOVAL) (Refer to 24 - HEAT-
ING & AIR CONDITIONING/PLUMBING/A/C
DISCHARGE LINE - REMOVAL) Install plugs in, or
tape over all of the opened refrigerant fittings.
(6) Remove the bolts that secure the compressor to
the mounting bracket (Fig. 2) or (Fig. 3) or (Fig. 4).
(7) Remove the compressor from the mounting
bracket.
Fig. 2 A/C COMPRESSOR - 2.4L ENGINE
1 - COMPRESSOR BOLT
2 - COMPRESSOR BOLT
3 - COMPRESSOR CLUTCH AND PULLY
4 - IDLER PULLEY
5 - ENGINE BLOCK
6 - A/C COMPRESSOR
KJPLUMBING 24 - 43
A/C COMPRESSOR (Continued)

EVAPORATIVE EMISSIONS
TABLE OF CONTENTS
page page
EVAPORATIVE EMISSIONS
DESCRIPTION - EVAPORATION CONTROL
SYSTEM............................24
SPECIFICATIONS
TORQUE............................26
EVAP/PURGE SOLENOID
DESCRIPTION.........................27
OPERATION...........................27
REMOVAL.............................27
INSTALLATION.........................27
FUEL FILLER CAP
DESCRIPTION.........................27
OPERATION...........................27
LEAK DETECTION PUMP
DESCRIPTION.........................27
OPERATION...........................28
REMOVAL.............................28INSTALLATION.........................28
ORVR
DESCRIPTION.........................29
OPERATION...........................29
P C V VA LV E
DESCRIPTION.........................29
OPERATION...........................31
DIAGNOSIS AND TESTING - PCV VALVE.....31
REMOVAL.............................32
INSTALLATION.........................32
VACUUM LINES
DESCRIPTION.........................33
VAPOR CANISTER
DESCRIPTION.........................33
OPERATION...........................33
REMOVAL.............................33
INSTALLATION.........................33
EVAPORATIVE EMISSIONS
DESCRIPTION - 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 the control valve located in the top section of
the fuel pump module, through the fuel management
valve, and through vent hoses and tubes to a char-
coal filled evaporative canister. The canister tempo-
rarily holds the vapors. The Powertrain Control
Module (PCM) allows intake manifold vacuum to
draw vapors into the combustion chambers during
certain operating conditions.
Gas powered engines use a duty cycle purge sys-
tem. The PCM controls vapor flow by operating theduty 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.
Vehicles powered with gasoline engines are also
equipped with ORVR (On-Board Refueling Vapor
Recovery). Refer to ORVR for additional information.
NOTE: The evaporative system uses specially man-
ufactured lines/hoses. If replacement becomes nec-
essary, only use fuel resistant, low permeation
hose.
Certain components can be found in (Fig. 1).
25 - 24 EVAPORATIVE EMISSIONSKJ