
FUEL RAIL
DESCRIPTION - 3.9L/5.2L/5.9L
The fuel injector rail is used to attach the fuel
injectors to the engine. It is mounted to the engine
(Fig. 25).
DESCRIPTION - 8.0L
The fuel injector rail is used to attach the fuel
injectors to the engine. The fuel rail supplies the nec-
essary fuel to each individual fuel injector and is
mounted to the lower half of the two-piece intakemanifold (Fig. 26). The metal, one-piece fuel rail is
not repairable.
OPERATION - 3.9L/5.2L/5.9L
High pressure from the fuel pump is routed to the
fuel rail. The fuel rail then supplies the necessary
fuel to each individual fuel injector.
A fuel pressure test port is located on the fuel rail.
A quick-connect fitting with a safety latch clip is
used to attach the fuel line to the fuel rail.
The fuel rail is not repairable.
CAUTION: The left and right sections of the fuel rail
are connected with a flexible connecting hose. Do
not attempt to separate the rail halves at this con-
necting hose. Due to the design of this connecting
hose, it does not use any clamps. Never attempt to
install a clamping device of any kind to the hose.
When removing the fuel rail assembly for any rea-
son, be careful not to bend or kink the connecting
hose.
OPERATION - 8.0L
High pressure from the fuel pump is routed to the
fuel rail. The fuel rail then supplies the necessary
fuel to each individual fuel injector.
Fig. 24 Locknut Removal/InstallationÐTYPICAL
1 - SPECIAL TOOL 6856
2 - LOCKNUT
Fig. 25 Fuel RailÐ3.9/5.2/5.9L EngineÐTypical
1 - FUEL RAIL CONNECTING HOSE
2 - FUEL RAIL
3 - MOUNTING BOLTS (4)
Fig. 26 Fuel RailÐ8.0L Engine
1 - FUEL RAIL
2 - ELECTRICAL CONNECTOR
3 - MOUNTING BOLTS (6)
4 - INTAKE MANIFOLD LOWER HALF
5 - FUEL PRESSURE TEST PORT
6 - FUEL INJECTORS (10)
BR/BEFUEL DELIVERY - GASOLINE 14 - 15
FUEL PUMP MODULE (Continued)

A fuel pressure test port is located on the fuel rail.
A quick-connect fitting with a safety latch clip is
used to attach the fuel line to the fuel rail.
The fuel rail is not repairable.
REMOVAL - 3.9L/5.2L/5.9L
WARNING: THE FUEL SYSTEM IS UNDER A CON-
STANT PRESSURE (EVEN WITH ENGINE TURNED
OFF). BEFORE SERVICING FUEL RAIL ASSEMBLY,
FUEL SYSTEM PRESSURE MUST BE RELEASED.
To release fuel pressure, refer to Fuel System Pres-
sure Release Procedure found in this group.
CAUTION: The left and right fuel rails are replaced
as an assembly. Do not attempt to separate the rail
halves at the connecting hose (Fig. 27). Due to the
design of this connecting hose, it does use any
clamps. Never attempt to install a clamping device
of any kind to the hose. When removing the fuel rail
assembly for any reason, be careful not to bend or
kink the connecting hose.
(1) Remove negative battery cable at battery.
(2) Remove air cleaner.
(3) Perform fuel pressure release procedure.
(4) Remove throttle body from intake manifold.
Refer to Throttle Body removal in this group.
(5) If equipped with air conditioning, remove the
A-shaped A/C compressor-to-intake manifold support
bracket (three bolts) (Fig. 28).(6) Disconnect electrical connectors at all fuel
injectors. To remove connector refer to (Fig. 29). 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.
Fig. 27 Fuel Rail AssemblyÐTypical
1 - FUEL RAIL CONNECTING HOSE
2 - FUEL RAIL
3 - MOUNTING BOLTS (4)
Fig. 28 A/C Compressor Support BracketÐTypical
1 - AIR CONDITIONING COMPRESSOR SUPPORT BRACKET
2 - MOUNTING BOLTS
Fig. 29 Remove/Install Fuel Injector Connector
14 - 16 FUEL DELIVERY - GASOLINEBR/BE
FUEL RAIL (Continued)

(7) 3.9L (V-6) engine only: Disconnect electrical
connector at intake manifold air temperature sensor.
Do not remove sensor.
(8) Disconnect fuel tube (line) at side of fuel rail.
Refer to Quick-Connect Fittings for procedures,
(9) Remove the remaining fuel rail mounting bolts.
(10) Gently rock and pull theleftfuel rail until
the fuel injectors just start to clear the intake mani-
fold. Gently rock and pull therightfuel rail until
the fuel injectors just start to clear the intake mani-
fold. Repeat this procedure (left/right) until all fuel
injectors have cleared the intake manifold.
(11) Remove fuel rail (with injectors attached)
from engine.
(12) Remove the clip(s) retaining the injector(s) to
fuel rail (Fig. 30) or (Fig. 31).
REMOVAL - 8.0L
WARNING: THE FUEL SYSTEM IS UNDER A CON-
STANT PRESSURE EVEN WITH THE ENGINE OFF.
BEFORE SERVICING FUEL RAIL, FUEL SYSTEM
PRESSURE MUST BE RELEASED.
(1) Remove negative battery cable at battery.
(2) Remove air cleaner housing and tube.
(3) Perform fuel pressure release procedure. Refer
to Fuel Delivery System section of this group.
(4) Disconnect throttle body linkage and remove
throttle body from intake manifold. Refer to Throttle
Body removal in this group.
(5) Remove ignition coil pack and bracket assem-
bly (Fig. 32) at intake manifold and right engine
valve cover (four bolts).
(6) Remove upper half of intake manifold. Refer to
Engines for procedures.
Fig. 30 Fuel Injector MountingÐTypical
1 - CLIP
2 - INJECTOR
3 - FUEL RAIL
Fig. 31 Injector Retaining ClipsÐTypical Injector
1 - PLIERS
2 - INJECTOR CLIP
3 - FUEL INJECTOR
4 - FUEL RAIL
Fig. 32 Ignition Coil Pack and Mounting BracketÐ
8.0L V-10 Engine
1 - COIL PACKS AND BRACKET
2 - MOUNTING BOLTS (4)
BR/BEFUEL DELIVERY - GASOLINE 14 - 17
FUEL RAIL (Continued)

(7) Disconnect electrical connectors at all fuel
injectors. To remove connector refer to (Fig. 33). 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.
(8) Disconnect fuel line quick-connect fitting at
left-rear end of fuel rail. A special 3/8 inch fuel line
disconnection tool will be necessary.
(9) Remove the six fuel rail mounting bolts from
the lower half of intake manifold (Fig. 34).
(10) Gently rock and pull theleftfuel rail until
the fuel injectors just start to clear the intake mani-
fold. Gently rock and pull therightfuel rail until
the fuel injectors just start to clear the intake mani-
fold. Repeat this procedure (left/right) until all fuel
injectors have cleared the intake manifold.
(11) Remove fuel rail (with injectors attached)
from engine.
(12) Remove the clip(s) retaining the injector(s) to
fuel rail (Fig. 30) or (Fig. 31).
INSTALLATION - 3.9L/5.2L/5.9L
(1) Apply a small amount of engine oil to each fuel
injector o-ring. This will help in fuel rail installation.
(2) Install injector(s) and injector clip(s) to fuel
rail.
(3) Position the fuel rail/fuel injector assembly to
the injector openings on the intake manifold.(4) Guide each injector into the intake manifold.
Be careful not to tear the injector o-ring.
(5) Push therightfuel rail down until fuel injec-
tors have bottomed on injector shoulder. Push the
leftfuel rail down until fuel injectors have bottomed
on injector shoulder.
(6) Install fuel rail mounting bolts.
(7) Connect electrical connector to intake manifold
air temperature sensor.
(8) Connect electrical connectors at all fuel injec-
tors. To install connector, refer to (Fig. 29). Push con-
nector onto injector (1) and then push and lock red
colored slider (2). Verify connector is locked to injec-
tor by lightly tugging on connector.
(9) Install the A/C support bracket (if equipped).
(10) Install throttle body to intake manifold. Refer
to Throttle Body installation in this section of the
group.
(11) Install fuel tube (line) at side of fuel rail.
Refer to Quick-Connect Fittings for procedures.
(12) Install air cleaner.
(13) Connect battery cable to battery.
(14) Start engine and check for leaks.
Fig. 33 Remove/Install Fuel Injector Connector
Fig. 34 Fuel Rail Mounting BoltsÐ8.0L V-10
EngineÐTypical
1 - FUEL RAIL
2 - ELECTRICAL CONNECTOR
3 - MOUNTING BOLTS (6)
4 - INTAKE MANIFOLD LOWER HALF
5 - FUEL PRESSURE TEST PORT
6 - FUEL INJECTORS (10)
14 - 18 FUEL DELIVERY - GASOLINEBR/BE
FUEL RAIL (Continued)

INSTALLATION - 8.0L
(1) Apply a small amount of engine oil to each fuel
injector o-ring. This will help in fuel rail installation.
(2) Install injector(s) and injector clip(s) to fuel
rail.
NOTE: The fuel injector electrical connectors on all
10 injectors should be facing to the right (passen-
ger) side of the vehicle (Fig. 34).
(3) Position the fuel rail/fuel injector assembly to
the injector openings on the intake manifold.
(4) Guide each injector into the intake manifold.
Be careful not to tear the injector o-ring.
(5) Push therightfuel rail down until fuel injec-
tors have bottomed on injector shoulder. Push the
leftfuel rail down until fuel injectors have bottomed
on injector shoulder.
(6) Install the six fuel rail mounting bolts into the
lower half of intake manifold. Tighten bolts to 15
N´m (136 in. lbs.) torque.
(7) Connect electrical connectors at all fuel injec-
tors. To install connector, refer to (Fig. 33). Push con-
nector onto injector (1) and then push and lock red
colored slider (2). Verify connector is locked to injec-
tor by lightly tugging on connector. The injector wir-
ing harness is numerically tagged.
(8) Install upper half of intake manifold. Refer to
Engines for procedures.
(9) Connect main fuel line at fuel rail. Refer to
Quick-Connect Fittings for procedures.
(10) Install ignition coil pack and bracket assem-
bly at intake manifold and right engine valve cover
(four bolts).
(11) Install throttle body to intake manifold. Refer
to Throttle Body removal in this group.
(12) Install throttle body linkage to throttle body.
(13) Install air cleaner tube and housing.
(14) Install negative battery cable at battery.
(15) Start engine and check for leaks.
FUEL TANK
DESCRIPTION
The fuel tank is constructed of a plastic material.
Its main functions are for fuel storage and for place-
ment of the fuel pump module.
OPERATION
All models pass a full 360 degree rollover test
without fuel leakage. To accomplish this, fuel and
vapor flow controls are required for all fuel tank con-
nections.A rollover valve(s) is mounted into the top of the
fuel tank (or pump module). Refer to Emission Con-
trol System for rollover valve information.
An evaporation control system is connected to the
rollover valve(s) to reduce emissions of fuel vapors
into the atmosphere. When fuel evaporates from the
fuel tank, vapors pass through vent hoses or tubes to
a charcoal canister where they are temporarily held.
When the engine is running, the vapors are drawn
into the intake manifold. Certain models are also
equipped with a self-diagnosing system using a Leak
Detection Pump (LDP). Refer to Emission Control
System for additional information.
REMOVAL
WARNING: GASOLINE POWERED ENGINES: THE
FUEL SYSTEM IS UNDER A CONSTANT PRESSURE
EVEN WITH THE ENGINE OFF. BEFORE SERVICING
THE FUEL TANK, FUEL SYSTEM PRESSURE MUST
BE RELEASED. REFER TO THE FUEL SYSTEM
PRESSURE RELEASE PROCEDURE BEFORE SER-
VICING THE FUEL TANK.
Two different procedures may be used to drain fuel
tank (lowering tank or using DRB scan tool). When
equipped with a diesel engine, the DRB scan tool
cannot be used (no electric fuel pump).
The quickest draining procedure involves lowering
the fuel tank.
Gasoline Powered Engines:As an alternative
procedure, the electric fuel pump may be activated
allowing tank to be drained at fuel rail connection.
Refer to DRB scan tool for fuel pump activation pro-
cedures. Before disconnecting fuel line at fuel rail,
release fuel pressure. Refer to the Fuel System Pres-
sure Release Procedure in this group for procedures.
Attach end of special test hose tool number 6541,
6539, 6631 or 6923 at fuel rail disconnection (tool
number will depend on model and/or engine applica-
tion). Position opposite end of this hose tool to an
approved gasoline draining station. Activate fuel
pump and drain tank until empty.
If electric fuel pump is not operating, tank must be
lowered for fuel draining. Refer to following proce-
dures.
(1) Remove fuel tank filler tube cap.
(2) Perform Fuel System Pressure Release proce-
dure as described in this group.
(3) Gasoline Engines: Disconnect negative battery
cable at battery. Diesel Engines: Disconnect both neg-
ative battery cables at both batteries.
(4) Raise vehicle on hoist.
(5) Certain models are equipped with a separate
grounding wire (strap) connecting the fuel fill tube
assembly to the body. Disconnect wire by removing
screw.
BR/BEFUEL DELIVERY - GASOLINE 14 - 19
FUEL RAIL (Continued)

FUEL INJECTION - GASOLINE
TABLE OF CONTENTS
page page
FUEL INJECTION - GASOLINE
DIAGNOSIS AND TESTING.................28
VISUAL INSPECTION - 3.9L/5.2L/5.9L
ENGINES.............................28
VISUAL INSPECTION - 8.0L ENGINE........32
SPECIFICATIONS........................35
SPECIAL TOOLS.........................36
ACCELERATOR PEDAL
REMOVAL..............................37
INSTALLATION...........................37
CRANKSHAFT POSITION SENSOR
DESCRIPTION...........................38
OPERATION.............................38
REMOVAL..............................39
INSTALLATION...........................40
FUEL PUMP RELAY
DESCRIPTION...........................41
OPERATION.............................41
REMOVAL..............................41
INSTALLATION...........................41
IDLE AIR CONTROL MOTOR
DESCRIPTION...........................41
OPERATION.............................41
REMOVAL..............................42
INSTALLATION...........................42
INTAKE AIR TEMPERATURE SENSOR
DESCRIPTION...........................43
OPERATION.............................43
REMOVAL..............................43
INSTALLATION...........................43
MANIFOLD ABSOLUTE PRESSURE SENSOR
DESCRIPTION...........................44OPERATION.............................44
REMOVAL..............................45
INSTALLATION...........................45
O2 SENSOR
DESCRIPTION...........................46
OPERATION.............................46
REMOVAL..............................47
INSTALLATION...........................48
PTO SWITCH
DESCRIPTION...........................48
OPERATION.............................48
THROTTLE BODY
DESCRIPTION...........................48
OPERATION.............................48
REMOVAL..............................48
INSTALLATION...........................49
THROTTLE CONTROL CABLE
REMOVAL..............................50
INSTALLATION...........................50
THROTTLE POSITION SENSOR
DESCRIPTION...........................51
OPERATION.............................51
REMOVAL..............................51
INSTALLATION...........................52
FUEL INJECTOR
DESCRIPTION...........................53
OPERATION.............................53
DIAGNOSIS AND TESTING.................53
FUEL INJECTOR TEST...................53
REMOVAL..............................53
INSTALLATION...........................53
FUEL INJECTION - GASOLINE
VISUAL INSPECTIONÐ3.9L/5.2L/5.9L
ENGINES
A visual inspection for loose, disconnected or incor-
rectly routed wires and hoses should be made. This
should be done before attempting to diagnose or ser-
vice the fuel injection system. A visual check will
help spot these faults and save unnecessary test and
diagnostic time. A thorough visual inspection will
include the following checks:
(1) Verify that the three 32±way electrical connec-
tors are fully inserted into the connector of the pow-
ertrain control module (PCM) (Fig. 1).(2) Inspect the battery cable connections. Be sure
that they are clean and tight.
(3) Inspect fuel pump relay and air conditioning
compressor clutch relay (if equipped). Inspect the
ASD relay connections. Inspect starter motor relay
connections. Inspect relays for signs of physical dam-
age and corrosion. The relays are located in the
Power Distribution Center (PDC) (Fig. 2). Refer to
label on PDC cover for relay location.
(4) Inspect ignition coil connections. Verify that
coil secondary cable is firmly connected to coil (Fig.
3).
14 - 28 FUEL INJECTION - GASOLINEBR/BE

(5) Verify that distributor cap is correctly attached
to distributor. Be sure that spark plug cables are
firmly connected to the distributor cap and the spark
plugs are in their correct firing order. Be sure that
coil cable is firmly connected to distributor cap and
coil. Be sure that camshaft position sensor wire con-
nector (at the distributor) is firmly connected to har-
ness connector. Inspect spark plug condition. Refer to
8, Ignition. Connect vehicle to an oscilloscope and
inspect spark events for fouled or damaged spark
plugs or cables.
(6) Verify that generator output wire, generator
connector and ground wire are firmly connected to
the generator.(7) Inspect the system body grounds for loose or
dirty connections. Refer to 8, Wiring for ground loca-
tions.
(8) Verify positive crankcase ventilation (PCV)
valve operation. Refer to 25, Emission Control Sys-
tem for additional information. Verify PCV valve
hose is firmly connected to PCV valve and manifold
(Fig. 4).
(9) Inspect fuel tube quick-connect fitting-to-fuel
rail connections.
(10) Verify that hose connections to all ports of
vacuum fittings on intake manifold are tight and not
leaking.
Fig. 1 Powertrain Control Module (PCM)
1 - PCM MOUNTING BOLTS (3)
2 - POWERTRAIN CONTROL MODULE (PCM)
3 - (3) 32±WAY CONNECTORS
Fig. 2 Power Distribution Center (PDC)
1 - POWER DISTRIBUTION CENTER (PDC)
Fig. 3 Ignition CoilÐ3.9L/5.2L/5.9L EnginesÐTypical
1 - ACCESSORY DRIVE BELT TENSIONER
2 - COIL CONNECTOR
3 - IGNITION COIL
4 - COIL MOUNTING BOLTS
Fig. 4 PCV Valve
1 - P C V VA LV E
2 - PCV VALVE HOSE CONNECTIONS
BR/BEFUEL INJECTION - GASOLINE 14 - 29
FUEL INJECTION - GASOLINE (Continued)

(11) Inspect accelerator cable, transmission throt-
tle cable (if equipped) and cruise control cable con-
nections (if equipped). Check their connections to the
throttle arm of throttle body for any binding or
restrictions.
(12) If equipped with vacuum brake booster, verify
that vacuum booster hose is firmly connected to fit-
ting on intake manifold. Also check connection to
brake vacuum booster.
(13) Inspect the air cleaner inlet and air cleaner
element for dirt or restrictions.
(14) Inspect radiator grille area, radiator fins and
air conditioning condenser for restrictions.
(15) Verify that the intake manifold air tempera-
ture sensor wire connector is firmly connected to har-
ness connector (Fig. 5).
(16) Verify that MAP sensor electrical connector is
firmly connected to MAP sensor (Fig. 6). Also verify
that rubber L-shaped fitting from MAP sensor to the
throttle body is firmly connected (Fig. 7).
(17) Verify that fuel injector wire harness connec-
tors are firmly connected to injectors in the correct
order. Each harness connector is numerically tagged
with the injector number (INJ 1, INJ 2 etc.) of its
corresponding fuel injector and cylinder number.
(18) Verify harness connectors are firmly con-
nected to idle air control (IAC) motor, throttle posi-
tion sensor (TPS) and manifold absolute pressure
(MAP) sensor (Fig. 6).
(19) Verify that wire harness connector is firmly
connected to the engine coolant temperature sensor
(Fig. 8).
(20) Raise and support the vehicle.(21) Verify oxygen sensor wire connectors are
firmly connected to the sensors. Inspect sensors and
connectors for damage (Fig. 9), (Fig. 10) or (Fig. 11).
(22) Inspect for pinched or leaking fuel tubes.
Inspect for pinched, cracked or leaking fuel hoses.
Fig. 5 Air Temperature
1 - INTAKE MANIFOLD AIR TEMPERATURE SENSOR
2 - ELECTRICAL CONNECTOR
Fig. 6 Sensor and IAC Motor LocationÐTypical (V-8
Shown)
1 - MAP SENSOR
2 - IDLE AIR CONTROL MOTOR
3 - THROTTLE POSITION SENSOR
Fig. 7 Rubber L-Shaped FittingÐMAP Sensor-to-
Throttle BodyÐ3.9L/5.2L/5.9L Engines
1 - MAP SENSOR
2 - RUBBER FITTING
3 - IDLE AIR PASSAGE
14 - 30 FUEL INJECTION - GASOLINEBR/BE
FUEL INJECTION - GASOLINE (Continued)