Control JEEP GRAND CHEROKEE 2002 WJ / 2.G Workshop Manual

(6) Remove accessory drive belt (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
REMOVAL).
(7) Disconnect generator electrical connections.
(8) Unbolt the generator and move it away from
the intake manifold for clearance.
(9) Disconnect air conditioning compressor electri-
cal connections.
(10) Unbolt the air conditioning compressor and
move it away from the intake manifold for clearance.
(11) Disconnect left and right radio suppressor
straps.
(12) Disconnect and remove ignition coil towers
(Refer to 8 - ELECTRICAL/IGNITION CONTROL/
IGNITION COIL - REMOVAL).
(13) Remove top oil dipstick tube retaining bolt
and ground strap.
(14) Bleed pressure from fuel system (Refer to 14 -
FUEL SYSTEM/FUEL DELIVERY - STANDARD
PROCEDURE).
(15) Remove fuel rail (Refer to 14 - FUEL SYS-
TEM/FUEL DELIVERY/FUEL RAIL - REMOVAL).
(16) Remove throttle body assembly and mounting
bracket.
(17) Drain cooling system below coolant tempera-
ture level (Refer to 7 - COOLING - STANDARD
PROCEDURE).
(18) Remove coolant temperature sensor (Refer to
7 - COOLING/ENGINE/ENGINE COOLANT TEMP
SENSOR - REMOVAL).
(19) Remove cowl to hood seal. (Refer to 23 -
BODY/WEATHERSTRIP/SEALS/COWL WEATHER-
STRIP - REMOVAL).
(20) Remove right side engine lifting stud.
(21) Remove intake manifold retaining fasteners,
in reverse order of tightening sequence (Fig. 105).
NOTE: Intake must be lifted upward and level in the
front and rear to clear the cowl. Interference with
the cowl will occur during removal.
(22) Remove intake manifold.
CLEANING
NOTE: There is NO approved repair procedure for
the intake manifold. If severe damage is found dur-
ing inspection, the intake manifold must be
replaced.
Before installing the intake manifold thoroughly
clean the mating surfaces. Use a suitable cleaning
solvent, then air dry.
INSPECTION
(1) Inspect the intake sealing surface for cracks,
nicks and distortion.(2) Inspect the intake manifold vacuum hose fit-
tings for looseness or blockage.
(3) Inspect the manifold to throttle body mating
surface for cracks, nicks and distortion.
INSTALLATION
(1) Install intake manifold gaskets.
(2) Install intake manifold.
(3) Install intake manifold retaining bolts and
tighten in sequence shown in (Fig. 106) to 12 N´m
(105 in. lbs.).
(4) Install left and right radio suppressor straps.
(5) Install throttle body assembly.
(6) Install throttle cable bracket.
Fig. 105 Intake Manifold Tightening Sequence
Fig. 106 Intake Manifold Tightening Sequence
WJENGINE - 4.7L 9 - 137
INTAKE MANIFOLD (Continued)

(7) Connect throttle cable and speed control cable
to throttle body.
(8) Install fuel rail (Refer to 14 - FUEL SYSTEM/
FUEL DELIVERY/FUEL RAIL - INSTALLATION).
(9) Install ignition coil towers (Refer to 8 - ELEC-
TRICAL/IGNITION CONTROL/IGNITION COIL -
INSTALLATION).
(10) Install coolant temperature sensor (Refer to 7
- COOLING/ENGINE/ENGINE COOLANT TEMP
SENSOR - INSTALLATION).
(11) Connect electrical connectors for the following
components:
²Manifold Absolute Pressure (MAP) Sensor
²Intake Air Temperature (IAT) Sensor
²Throttle Position (TPS) Sensor
²Coolant Temperature (CTS) Sensor
²Idle Air Control (IAC) Motor
²Ignition coil towers
²Fuel injectors
(12) Install top oil dipstick tube retaining bolt and
ground strap.
(13) Install right side engine lifting stud.
(14) Install generator including electrical connec-
tions (Refer to 8 - ELECTRICAL/CHARGING/GEN-
ERATOR - INSTALLATION).
(15) Connect Vapor purge hose, Brake booster
hose, Speed control servo hose, Positive crankcase
ventilation (PCV) hose.
(16) Install air conditioning compressor including
electrical connections.
(17) Fill cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE).
(18) Install accessory drive belt (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
INSTALLATION).
(19) Install cowl to hood seal (Refer to 23 - BODY/
WEATHERSTRIP/SEALS/COWL WEATHERSTRIP -
INSTALLATION).
(20) Install air cleaner housing and throttle body
resonator. Tighten resonator bolts 4.5 N´m (40 in.
lbs.).
(21) Connect negative cable to battery.
EXHAUST MANIFOLD - LEFT
DESCRIPTION
The exhaust manifolds are log style with a pat-
ented flow enhancing design to maximize perfor-
mance. The exhaust manifolds are made of high
silicon molybdenum cast iron. A perforated core
graphite exhaust manifold gasket is used to improve
sealing to the cylinder head. The exhaust manifolds
are covered by a three layer laminated heat shield
for thermal protection and noise reduction. The heat
shields are fastened with a torque prevailing nutthat is backed off slightly to allow for the thermal
expansion of the exhaust manifold.
REMOVAL
(1) Disconnect negative cable for battery.
(2) Hoist vehicle.
(3) Disconnect exhaust pipe at manifold.
(4) Lower vehicle.
(5) Remove air cleaner housing and tube.
(6) Remove the front two exhaust heat shield
retaining fasteners. Raise vehicle and remove the
fasteners at rear of heat shield.
(7) Remove heat shield (Fig. 107).
(8) Lower vehicle and remove the upper exhaust
manifold retaining bolts (Fig. 107).
(9) Raise vehicle and remove the lower exhaust
manifold retaining bolts (Fig. 107).
(10) Remove exhaust manifold and gasket (Fig.
107). Manifold is removed from below the engine
compartment.
CLEANING
(1) Clean the exhaust manifold using a suitable
cleaning solvent, then allow to air dry.
(2) Clean all gasket residue from the manifold
mating surface.
INSPECTION
(1) Inspect the exhaust manifold for cracks in the
mating surface and at every mounting bolt hole.
(2) Using a straight edge and a feeler gauge, check
the mating surface for warp and twist.
(3) Inspect the manifold to exhaust pipe mating
surface for cracks, gouges, or other damage that
would prevent sealing.
INSTALLATION
(1) Install exhaust manifold and gasket from below
engine compartment.
(2) Install lower exhaust manifold fasteners (Fig.
107). DO NOT tighten until all fasteners are in
place.
(3) Lower vehicle and install upper exhaust mani-
fold fasteners (Fig. 107). Tighten all manifold bolts
starting at center and working outward to 25 N´m
(18 ft. lbs.).
CAUTION: Over tightening heat shield fasteners,
may cause shield to distort and/or crack.
(4) Install exhaust manifold heat shield (Fig. 107).
Tighten fasteners to 8 N´m (72 in. lbs.), then loosen
45 degrees.
(5) Install air cleaner housing and tube.
(6) Connect exhaust pipe to manifold.
(7) Connect negative cable to battery.
9 - 138 ENGINE - 4.7LWJ
INTAKE MANIFOLD (Continued)

INSPECTION
(1) Inspect the exhaust manifold for cracks in the
mating surface and at every mounting bolt hole.
(2) Using a straight edge and a feeler gauge, check
the mating surface for warp and twist.
(3) Inspect the manifold to exhaust pipe mating
surface for cracks, gouges, or other damage that
would prevent sealing.
INSTALLATION
(1) Install exhaust manifold and gasket from below
engine compartment.
(2) Install lower exhaust manifold fasteners. DO
NOT tighten until all fasteners are in place.
(3) Lower vehicle and install upper exhaust mani-
fold fasteners. Tighten all manifold bolts starting at
center and working outward to 25 N´m (18 ft. lbs.).
CAUTION: Over tightening heat shield fasteners,
may cause shield to distort and/or crack.
(4) Install exhaust manifold heat shield. Tighten
fasteners to 8 N´m (72 in. lbs.), then loosen 45
degrees.
(5) Install starter and fasteners.
(6) Connect exhaust pipe to manifold.
(7) Connect heater hoses at engine.
(8) Install fastener attaching A/C accumulator.
(9) Install A/C compressor and fasteners.
(10) Install accessory drive belt (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
INSTALLATION).
(11) Install washer bottle and battery tray assem-
bly.
(12) Install PDC.
(13) Install battery and connect cables.
(14) Fill cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE).
VALVE TIMING
DESCRIPTION - TIMING DRIVE SYSTEM
The timing drive system has been designed to pro-
vide quiet performance and reliability to support a
non-free wheelingengine. Specifically the intake
valves are non-free wheeling and can be easily dam-
aged with forceful engine rotation if camshaft-to-
crankshaft timing is incorrect. The timing drive
system consists of a primary chain and two second-
ary timing chain drives (Fig. 109).
OPERATION - TIMING DRIVE SYSTEM
The primary timing chain is a single inverted tooth
type. The primary chain drives the large fifty tooth
idler sprocket directly from a 25 tooth crankshaftsprocket. Primary chain motion is controlled by a
pivoting leaf spring tensioner arm and a fixed guide.
The arm and the guide both use nylon plastic wear
faces for low friction and long wear. The primary
chain receives oil splash lubrication from the second-
ary chain drive and oil pump leakage. The idler
sprocket assembly connects the primary and second-
ary chain drives. The idler sprocket assembly con-
sists of two integral thirty tooth sprockets and a fifty
tooth sprocket that is splined to the assembly. The
spline joint is a non ± serviceable press fit anti rattle
type. A spiral ring is installed on the outboard side of
the fifty tooth sprocket to prevent spline disengage-
ment. The idler sprocket assembly spins on a station-
ary idler shaft. The idler shaft is press-fit into the
cylinder block. A large washer on the idler shaft bolt
and the rear flange of the idler shaft are used to con-
trol sprocket thrust movement. Pressurized oil is
routed through the center of the idler shaft to pro-
vide lubrication for the two bushings used in the
idler sprocket assembly.
There are two secondary drive chains, both are
inverted tooth type, one to drive the camshaft in each
SOHC cylinder head. There are no shaft speed
changes in the secondary chain drive system. Each
secondary chain drives a thirty tooth cam sprocket
directly from the thirty tooth sprocket on the idler
sprocket assembly. A fixed chain guide and a hydrau-
lic oil damped tensioner are used to maintain tension
in each secondary chain system. The hydraulic ten-
sioners for the secondary chain systems are fed pres-
surized oil from oil reservoir pockets in the block.
Each tensioner also has a mechanical ratchet system
that limits chain slack if the tensioner piston bleeds
down after engine shut down. The tensioner arms
and guides also utilize nylon wear faces for low fric-
tion and long wear. The secondary timing chains
receive lubrication from a small orifice in the ten-
sioners. This orifice is protected from clogging by a
fine mesh screen which is located on the back of the
hydraulic tensioners.
STANDARD PROCEDURE
STANDARD PROCEDURE - ENGINE TIMING -
VERIFICATION
CAUTION: The 4.7L is a non free-wheeling design
engine. Therefore, correct engine timing is critical.
NOTE: Components referred to as left hand or right
hand are as viewed from the drivers position inside
the vehicle.
WJENGINE - 4.7L 9 - 141
EXHAUST MANIFOLD - RIGHT (Continued)

HEAT SHIELDS
DESCRIPTION
Heat shields are needed to protect both the vehicle
and the environment from the high temperatures
developed by the catalytic converter. The catalytic
converter releases additional heat into the exhaust
system. Under severe operating conditions, the tem-
perature increases in the area of the converter. Such
conditions can exist when the engine misfires or oth-
erwise does not operate at peak efficiency (Fig. 17).
MUFFLER
DESCRIPTION
Both the 4.0L and 4.7L engines use a stainless
steel muffler to control exhaust noise levels and
exhaust back pressure. The muffler and tailpipe are
a one piece assembly (Fig. 18).
REMOVAL
All original equipment exhaust systems are manu-
factured with the tailpipe welded to the muffler. Ser-
vice replacement mufflers and tailpipes are either
clamped together or welded together.
WARNING: IF TORCHES ARE USED WHEN WORK-
ING ON THE EXHAUST SYSTEM, DO NOT ALLOW
THE FLAME NEAR THE FUEL LINES.
(1) Raise and support the vehicle.
(2) Saturate the bolts and nuts with heat valve
lubricant. Allow 5 minutes for penetration.(3) Loosen the exhaust clamp on the catalytic con-
verter to muffler connection (Fig. 19).
(4) Heat the catalytic converter-to-muffler connec-
tion with a torch until the metal becomes cherry red.
(5) While the metal is still cherry red, remove the
tailpipe/muffler assembly from the catalytic con-
verter.
(6) Remove the tailpipe from the tailpipe hanger
(Fig. 20).
(7) Remove the tailpipe/muffler assembly (Fig. 20).
INSTALLATION
(1) If the tailpipe hanger assembly was removed,
install the hanger to the frame. Tighten the bolts to
22 N´m (192 in. lbs.) torque.
(2) Position the tailpipe and muffler onto the
tailpipe hanger (Fig. 20) .
(3) Install the muffler onto the catalytic converter.
Make sure that the tailpipe has sufficient clearance
from the floor pan. Install exhaust clamp and tighten
the nuts to 47 N´m (35 ft. lbs.) torque (Fig. 19) .
(4) Lower the vehicle.
(5) Start the engine and inspect for exhaust leaks
and exhaust system contact with the body panels.
Adjust the alignment, if needed.
Fig. 17 Front and Rear Floor Pan Heat Shields
Typical
1 - REAR FLOOR PAN HEAT SHIELD
2 - HEAT SHIELD RETAINING NUTS (QTY 8)
3 - FRONT FLOOR PAN HEAT SHIELD
Fig. 18 Muffler and Tailpipe
1 - CATALYTIC CONVERTER
2 - TAILPIPE HANGER
3 - TAILPIPE
4 - MUFFLER
11 - 12 EXHAUST SYSTEMWJ

TAILPIPE
DESCRIPTION
The tailpipe is also made of stainless steel. (Fig.
18) .
OPERATION
The Tailpipe channels the exhaust out of the muf-
fler and out from under the vehicle to control noise
and prevent exhaust gas fumes from entering the
passenger compartment
Fig. 19 Installing Exhaust Clamps
1 - CATALYTIC CONVERTER
2 - MUFFLER
Fig. 20 Muffler and Tailpipe
1 - CATALYTIC CONVERTER
2 - TAILPIPE HANGER
3 - TAILPIPE
4 - MUFFLER
WJEXHAUST SYSTEM 11 - 13
MUFFLER (Continued)

FUEL DELIVERY
DESCRIPTION
The fuel delivery system consists of:
²the fuel pump module containing the electric
fuel pump, fuel gauge sending unit (fuel level sensor)
and a separate fuel filter located at bottom of pump
module
²a separate combination fuel filter/fuel pressure
regulator
²fuel tubes/lines/hoses
²quick-connect fittings
²fuel injector rail
²fuel injectors
²fuel tank
²fuel tank filler/vent tube assembly
²fuel tank filler tube cap
²accelerator pedal
²throttle cable
OPERATION
The fuel tank assembly consists of: the fuel tank,
fuel tank shield, fuel tank straps, fuel pump module
assembly, fuel pump module locknut/gasket, and fuel
tank check valve (refer to Emission Control System
for fuel tank check valve information).
A fuel filler/vent tube assembly using a pressure/
vacuum, 1/4 turn fuel filler cap is used. The fuel
filler tube contains a flap door located below the fuel
fill cap.
Also to be considered part of the fuel system is the
evaporation control system. This is designed to
reduce the emission of fuel vapors into the atmo-
sphere. The description and function of the Evapora-
tive Control System is found in Emission Control
Systems.
Both fuel filters (at bottom of fuel pump module
and within fuel pressure regulator) are designed for
extended service. They do not require normal sched-
uled maintenance. Filters should only be replaced if
a diagnostic procedure indicates to do so.
DIAGNOSIS AND TESTING
FUEL PRESSURE LEAK DOWN TEST
Use this test in conjunction with the Fuel Pump
Pressure Test and Fuel Pump Capacity Test.
Check Valve Operation:The electric fuel pump
outlet contains a one-way check valve to prevent fuel
flow back into the tank and to maintain fuel supply
line pressure (engine warm) when pump is not oper-
ational. It is also used to keep the fuel supply line
full of gasoline when pump is not operational. After
the vehicle has cooled down, fuel pressure may drop
to 0 psi (cold fluid contracts), but liquid gasoline willremain in fuel supply line between the check valve
and fuel injectors.Fuel pressure that has
dropped to 0 psi on a cooled down vehicle
(engine off) is a normal condition.When the elec-
tric fuel pump is activated, fuel pressure should
immediately(1±2 seconds) rise to specification.
Abnormally long periods of cranking to restart a
hotengine that has been shut down for a short
period of time may be caused by:
²Fuel pressure bleeding past a fuel injector(s).
²Fuel pressure bleeding past the check valve in
the fuel pump module.
²A defective fuel filter/pressure regulator.
Two #6539, 5/16º, Fuel Line Pressure Test Adapter
Hose Tools are required for the following tests.
(1) Release fuel system pressure. Refer to Fuel
Pressure Release Procedure.
(2) Raise vehicle.
Fuel Line Identification:The fuel filter/pressure
regulator is located in front of the fuel tank and
above the rear axle. It is transversely mounted to a
chassis crossmember (left-to-right). The filter/regula-
tor is equipped with 3 fuel line fittings (2 at one end
and 1 at the other end). The single fitting facing the
left side of the vehicle is the supply line to the fuel
rail (Fig. 1) . The 2 fittings facing the right side of
the vehicle are connected to the fuel tank. Of these 2
fittings, the fitting towards thefrontis used for fuel
return to the fuel tank. The fitting towards therear
is a pressure line. Thisrearfitting must be discon-
nected for the following step.
(3) See previous step. Disconnect fuel pressure line
atrearof filter/regulator. This is a 5/169quick-con-
nect fitting (Fig. 1) . Refer to Quick-Connect Fittings
for procedures.
(4) Obtain correct Fuel Line Pressure Test Adapter
Hose Tool # 6539 for 5/16º fuel lines. Connect one
end of this Special Tool into the disconnected fuel
pressure line. Connect the other end of the Tool into
fitting on filter/regulator.
(5) Lower vehicle.
(6) Disconnect the fuel inlet line at fuel rail. Refer
to Quick-Connect Fittings for procedures. On some
engines, air cleaner housing removal may be neces-
sary before fuel line disconnection.
(7) Obtain a second Fuel Line Pressure Test
Adapter Hose Tool # 6539 for 5/16º fuel lines. Con-
nect this tool between disconnected fuel line and fuel
rail (Fig. 2) .
(8) Connect the 0-414 kPa (0-60 psi) fuel pressure
test gauge (from Gauge Set 5069) to the test port on
the appropriate Adaptor Tool.NOTE: The DRB III
Scan Tool along with the PEP module, the 500
psi pressure transducer, and the transducer-to-
test port adapter may also be used in place of
the fuel pressure gauge.
14 - 2 FUEL DELIVERYWJ

SPECIAL TOOLS
FUEL SYSTEM
FUEL FILTER/PRESSURE
REGULATOR
DESCRIPTION
The combination fuel filter/pressure regulator is
located in front of the fuel tank and above the rear
axle (Fig. 3). It is transversely mounted to a chassis
crossmember (left-to-right).Fuel Line Identifica-
tion:The filter/regulator is equipped with 3 fuel line
fittings (2 at one end and 1 at the other end). The
single fitting facing the left side of the vehicle is the
supply line to the fuel rail (Fig. 3). The 2 fittings fac-
ing the right side of the vehicle are connected to the
fuel tank. Of these 2 fittings, the fitting towards the
frontis used for fuel return to the fuel tank. The fit-
ting towards therearis a pressure line.
OPERATION
Fuel Pressure Regulator Operation:The pres-
sure regulator is a mechanical device that is not con-
trolled by engine vacuum or the Powertrain Control
Module (PCM).
Spanner WrenchÐ6856
FITTING, AIR METERING - 6714
Adapters, Fuel Pressure TestÐ6539 and/or 6631
O2S (Oxygen Sensor) Remover/InstallerÐC-4907
Test Kit, Fuel PressureÐ5069
Test Kit, Fuel PressureÐC-4799-B
Fuel Line Removal ToolÐ6782
WJFUEL DELIVERY 14 - 5
FUEL DELIVERY (Continued)

(3) Apply a small amount of clean engine oil to
o-rings.
(4) Position filter/regulator to body and install 2
bolts. Tighten bolts to 3 N´m (30 in. lbs.) torque.
(5) Connect 3 fittings. Refer to Quick-Connect Fit-
tings.
(6) Connect negative battery cable to battery.
(7) Start engine and check for leaks.
FUEL LEVEL SENDING UNIT /
SENSOR
DESCRIPTION
The fuel gauge sending unit (fuel level sensor) is
attached to the side of the fuel pump module. The
sending unit consists of a float, an arm, and a vari-
able resistor track (card).
OPERATION
The fuel pump module has 4 different circuits
(wires). Two of these circuits are used for the fuel
gauge sending unit for fuel gauge operation, and for
certain OBD II emission requirements. The other 2
wires are used for electric fuel pump operation.
For Fuel Gauge Operation:A constant input
voltage source of about 12 volts (battery voltage) is
supplied to the resistor track on the fuel gauge send-
ing unit. This is fed directly from the Powertrain
Control Module (PCM).NOTE: For diagnostic pur-
poses, this 12V power source can only be veri-fied with the circuit opened (fuel pump module
electrical connector unplugged). With the con-
nectors plugged, output voltages will vary from
about 0.6 volts at FULL, to about 8.6 volts at
EMPTY (about 8.6 volts at EMPTY for Jeep
models, and about 7.0 volts at EMPTY for
Dodge Truck models).The resistor track is used to
vary the voltage (resistance) depending on fuel tank
float level. As fuel level increases, the float and arm
move up, which decreases voltage. As fuel level
decreases, the float and arm move down, which
increases voltage. The varied voltage signal is
returned back to the PCM through the sensor return
circuit.
Both of the electrical circuits between the fuel
gauge sending unit and the PCM are hard-wired (not
multi-plexed). After the voltage signal is sent from
the resistor track, and back to the PCM, the PCM
will interpret the resistance (voltage) data and send
a message across the multi-plex bus circuits to the
instrument panel cluster. Here it is translated into
the appropriate fuel gauge level reading. Refer to
Instrument Panel for additional information.
For OBD II Emission Monitor Requirements:
The PCM will monitor the voltage output sent from
the resistor track on the sending unit to indicate fuel
level. The purpose of this feature is to prevent the
OBD II system from recording/setting false misfire
and fuel system monitor diagnostic trouble codes.
The feature is activated if the fuel level in the tank
is less than approximately 15 percent of its rated
capacity. If equipped with a Leak Detection Pump
(EVAP system monitor), this feature will also be acti-
vated if the fuel level in the tank is more than
approximately 85 percent of its rated capacity.
DIAGNOSIS AND TESTING - FUEL LEVEL
SENDING UNIT
The fuel level sending unit contains a variable
resistor (track). As the float moves up or down, elec-
trical resistance will change. Refer to Instrument
Panel and Gauges for Fuel Gauge testing. To test the
gauge sending unit only, it must be removed from
vehicle. The unit is part of the fuel pump module.
Refer to Fuel Pump Module Removal/Installation for
procedures. Measure the resistance across the send-
ing unit terminals. With float in up position, resis-
tance should be 20 ohms (+/- 5%). With float in down
position, resistance should be 270 ohms (+/- 5%).
REMOVAL
The fuel gauge sending unit (fuel level sensor) and
float assembly is located on the side of fuel pump
module (Fig. 6). The fuel pump module is located
within the fuel tank.
Fig. 5 Fuel Filter/Fuel Pressure Regulator Removal/
Installation
1 - FUEL FILTER/FUEL PRESSURE REGULATOR
2 - MOUNTING BOLTS (2)
WJFUEL DELIVERY 14 - 7
FUEL FILTER/PRESSURE REGULATOR (Continued)

(19) Disconnect test leads from relay cavities
immediately after testing.
FUEL PUMP PRESSURE TEST
Use this test in conjunction with other fuel system
tests. Refer to the Fuel Pump Capacity Test, Fuel
Pressure Leak Down Test and Fuel Pump Amperage
Test.
Check Valve Operation:The electric fuel pump
outlet contains a one-way check valve to prevent fuel
flow back into the tank and to maintain fuel supply
line pressure (engine warm) when pump is not oper-
ational. It is also used to keep the fuel supply line
full of gasoline when pump is not operational. After
the vehicle has cooled down, fuel pressure may drop
to 0 psi (cold fluid contracts), but liquid gasoline will
remain in fuel supply line between the check valve
and fuel injectors.Fuel pressure that has
dropped to 0 psi on a cooled down vehicle
(engine off) is a normal condition.When the elec-
tric fuel pump is activated, fuel pressure should
immediately(1±2 seconds) rise to specification.
The fuel system is equipped with a combination
fuel filter/fuel pressure regulator. The fuel pressure
regulator is not controlled by engine vacuum.
WARNING: THE FUEL SYSTEM IS UNDER CON-
STANT FUEL PRESSURE EVEN WITH THE ENGINE
OFF. BEFORE DISCONNECTING FUEL LINE AT
FUEL RAIL, THIS PRESSURE MUST BE RELEASED.REFER TO THE FUEL SYSTEM PRESSURE
RELEASE PROCEDURE.
(1) Remove pressure test port cap at fuel rail test
port (Fig. 12) or (Fig. 13) . Connect 0±414 kPa (0-60
psi) fuel pressure gauge (from gauge set 5069) to test
port pressure fitting on fuel rail (Fig. 14) .The DRB
III Scan Tool along with the PEP module, the
500 psi pressure transducer, and the transduc-
er-to-test port adapter may also be used in
place of the fuel pressure gauge.
(2) Start and warm engine and note pressure
gauge reading. The DRB scan tool may also be used
to power fuel pump. Fuel pressure should be 339 kPa
  34 kPa (49.2 psi   5 psi) at idle.
(3) If engine runs, but pressure is below 44.2 psi,
determine if fuel pump or filter/regulator is defective.
Proceed to next step:
(a) Check for a kinked fuel supply line some-
where between fuel rail and fuel pump module.
Fig. 11 FUEL PUMP RELAY - TYPE 3
TERMINAL LEGEND
NUMBER IDENTIFICATION
1 COIL BATTERY
2 COIL GROUND
3 COMMON FEED
4 NORMALLY CLOSED
5 NORMALLY OPEN
Fig. 12 Test Port Cap LocationÐ4.0L Engine
1 - INJ. #1
2 - INJ. #2
3 - INJ. #3
4 - INJ. #4
5 - INJ. #5
6 - INJ. #6
7 - FUEL INJECTOR RAIL
8 - FUEL DAMPER
9 - PRESSURE TEST PORT CAP
10 - MOUNTING BOLTS (4)
11 - QUICK-CONNECT FITTING
WJFUEL DELIVERY 14 - 11
FUEL PUMP (Continued)

(e) Use DRB scan tool to power fuel pump. If
pressure is now within specifications, replace fuel
filter/fuel pressure regulator.
(f) If pressure is still low, replace fuel pump
module.
(4) If operating pressure is above 54.2 psi, electric
fuel pump is OK, but fuel pressure regulator is defec-
tive. Replace fuel filter/fuel pressure regulator.
(5) Install test port cap to fuel rail test port.
FUEL PUMP MODULE
DESCRIPTION
The fuel pump module is installed in the top of the
fuel tank (Fig. 16). The fuel pump module (Fig. 17)
contains the following components:
²A separate fuel pick-up filter (strainer)
²An electric fuel pump
²A threaded locknut to retain module to tank
²A gasket between tank flange and module
²Fuel gauge sending unit (fuel level sensor)²Fuel supply tube (line) connection
²Fuel return tube (line) connection
The fuel gauge sending unit and pick-up filter may
be serviced separately. If the electrical fuel pump
requires service, the entire fuel pump module must
be replaced.
OPERATION
Refer to Fuel Pump, Fuel Filter/Fuel Pressure Reg-
ulator and Fuel Gauge Sending Unit.
REMOVAL
Fuel tank removal will be necessary for fuel pump
module removal.
WARNING: THE FUEL SYSTEM IS UNDER A CON-
STANT PRESSURE (EVEN WITH THE ENGINE OFF).
BEFORE SERVICING FUEL PUMP MODULE, FUEL
SYSTEM PRESSURE MUST BE RELEASED.
(1) Perform Fuel System Pressure Release Proce-
dure.
Fig. 16 FUEL TANK AND COMPONENTS
1 - FUEL PUMP MODULE 9 - TANK SUPPORT BRACKET (SMALL/FRONT)
2 - MODULE LOCK RING 10 - MODULE PIGTAIL HARNESS
3 - TANK SUPPORT BRACKETS (REAR) 11 - FUEL SUPPLY (PRESSURE) LINE
4 - CHECK VALVE 12 - FUEL RETURN LINE
5 - FUEL FILL HOSE 13 - SKID PLATE
6 - ORVR COMPONENTS 14 - TANK STRAPS (2)
7 - ORVR CONTROL VALVE 15 - FUEL TANK
8 - CONTROL VALVE LOCK RING
WJFUEL DELIVERY 14 - 13
FUEL PUMP (Continued)