VISUAL INSPECTIONÐ3.0L ENGINE
A visual inspection for loose, disconnected, or mis-
routed wires and hoses should be made before
attempting to diagnose or service the fuel injection
system. A visual check helps save unnecessary test
and diagnostic time. A thorough visual inspection will
include the following checks:(1) Check for correct spark plug cable routing.
Ensure that the cables are completely connected to
the spark plugs and distributor.
(2) Check ignition coil electrical connections (Fig.
62).
(3) Verify that the electrical connector is attached
to the Proportional Purge Solenoid (Fig. 63).
(4) Verify that vacuum connection at the duty cycle
Proportional Purge Solenoid valve is secure and not
leaking.
Fig. 60 Power Distribution Center (PDC)
Fig. 61 Power Brake Booster Hose
Fig. 62 Ignition Coil Electrical Connection
Fig. 63 Proportional Purge Solenoid Valve
14 - 52 FUEL SYSTEMNS
DIAGNOSIS AND TESTING (Continued)
terminals. Verify the connectors are fully inserted
into the socket of the PCM (Fig. 74). Ensure that
wires are not stretched or pulled out of the connector.
(24) Inspect fuses in the Power Distribution Cen-
ter (PDC). Verify all fuses and relays are fully
inserted into the PDC (Fig. 74). A label affixed to the
underside of the PDC cover identifies the relays and
fuses in the PDC.
(25) Check Battery Cable Connections.
(26) Check hose and wiring connections at fuel
pump module. Check that wiring connector is making
contact with terminals on pump.
VISUAL INSPECTIONÐ3.3/3.8L ENGINES
A visual inspection for loose, disconnected, or mis-
routed wires and hoses should be made before
attempting to diagnose or service the fuel injection
system. A visual check helps save unnecessary test
and diagnostic time. A thorough visual inspection will
include the following checks:
(1) Check ignition cable routing from the coil pack
to the spark plugs. Verify the cable are routed in the
correct order and are fully seated to the coil and
spark plug.(2) Check direct ignition system (DIS) coil electri-
cal connection for damage and a complete connection
to the coil pack (Fig. 75).
(3) Verify the camshaft position sensor electrical
connector is connected to the harness and not dam-
aged (Fig. 76).
(4) Ensure the engine temperature sensor electri-
cal connector is connected to the sensor and not dam-
aged (Fig. 77).
(5) Verify the quick connect fuel fitting is fully
inserted on the fuel supply tube.
(6) Check the oil pressure sending unit electrical
connection (Fig. 78).
Fig. 74 Powertrain Control Module (PCM)
Fig. 75 Ignition Coil Pack Electrical Connection
Fig. 76 Camshaft Position Sensor
NSFUEL SYSTEM 14 - 55
DIAGNOSIS AND TESTING (Continued)
FUEL SYSTEMÐ2.5L DIESEL ENGINE/2.0L GAS ENGINE
CONTENTS
page page
FUEL DELIVERY SYSTEMÐ2.0L ENGINE.... 28
FUEL DELIVERY SYSTEMÐ2.5L DIESEL
ENGINE.............................. 3
FUEL INJECTION SYSTEMÐ2.0L ENGINE . . . 32FUEL INJECTION SYSTEMÐ2.5L DIESEL
ENGINE............................. 43
GENERAL INFORMATION.................. 1
GENERAL INFORMATION
INDEX
page page
GENERAL INFORMATION
FUEL REQUIREMENTSÐ2.0L ENGINE....... 2
FUEL REQUIREMENTSÐ2.5L DIESEL........ 2GASOLINE/OXYGENATE BLENDS........... 2
INTRODUCTIONÐ2.0L ENGINE............. 2
INTRODUCTIONÐ2.5L DIESEL............. 1
GENERAL INFORMATION
INTRODUCTIONÐ2.5L DIESEL
Certain components of the fuel system on the 2.5L
diesel engine are controlled by the Bosch Engine con-
troller which is a Powertrain Control Module (PCM).
Refer to Powertrain Control Module in the Fuel
Injection SystemÐ2.5L Diesel Engine section of this
group for a list of items controlled by the PCM. The
Body Control Module (BCM) is mounted to a bracket
located inside the vehicle under the dashpanel to the
left of the steering column (Fig. 1). The PCM is
mounted at the base of the center console in front of
the Air Bag Module. (Fig. 2).
TheFuel Systemconsists of: the fuel tank, fuel
injection pump (engine mounted), fuel filter/water
separator, fuel tank module, electrical fuel gauge
sending unit, glow plugs, glow plug relay, PCM, and
all the electrical components that control the fuel
system. It also consists of fuel tubes/lines/hoses and
fittings, vacuum hoses, and fuel injector(s).
AFuel Return System.A separate fuel return
system is used. This will route excess fuel: from the
fuel injectors; through individual injector drain
tubes; through the fuel injection pump overflow
valve; and back to the fuel tank through a separate
fuel line.TheFuel Tank Assemblyconsists of: the fuel
tank, two pressure relief/rollover valves, fuel filler
tube, fuel tank module containing a fuel gauge send-
ing unit, and a pressure-vacuum filler cap.
Fig. 1 BCM Location
NS/GSFUEL SYSTEMÐ2.5L DIESEL ENGINE/2.0L GAS ENGINE 14 - 1
FUEL DELIVERY SYSTEMÐ2.5L DIESEL ENGINE
INDEX
page page
DESCRIPTION AND OPERATION
FUEL DRAIN TUBES..................... 7
FUEL FILTER/WATER SEPARATOR.......... 4
FUEL GAUGE SENDING UNIT.............. 4
FUEL HEATER RELAY.................... 8
FUEL HEATER.......................... 8
FUEL INJECTION PUMP.................. 5
FUEL INJECTORS....................... 6
FUEL SHUTDOWN SOLENOID............. 5
FUEL SYSTEM PRESSURE WARNING....... 3
FUEL TANK MODULE.................... 4
FUEL TANK............................ 3
FUEL TUBES/LINES/HOSES AND CLAMPSÐ
LOW-PRESSURE TYPE................. 6
HIGH-PRESSURE FUEL LINES............. 7
INTRODUCTION........................ 3
QUICK-CONNECT FITTINGSÐLOW PRESSURE
TYPE............................... 7
WASTEGATE (TURBOCHARGER)........... 8
DIAGNOSIS AND TESTING
AIR IN FUEL SYSTEM................... 11
FUEL HEATER RELAY TEST.............. 12
FUEL INJECTION PUMP TEST............. 12
FUEL INJECTOR SENSOR TEST........... 12
FUEL INJECTOR TEST.................. 12
FUEL SHUTDOWN SOLENOID TEST........ 13
FUEL SUPPLY RESTRICTIONS............ 13GENERAL INFORMATION................. 9
HIGH-PRESSURE FUEL LINE LEAK TEST.... 14
VISUAL INSPECTION..................... 9
WASTEGATE (TURBOCHARGER).......... 14
SERVICE PROCEDURES
AIR BLEED PROCEDURES............... 14
FUEL INJECTION PUMP TIMING........... 15
REMOVAL AND INSTALLATION
ACCELERATOR PEDAL.................. 16
AIR CLEANER ELEMENT................. 16
FUEL DRAIN TUBES.................... 16
FUEL FILTER/WATER SEPARATOR......... 16
FUEL HEATER RELAY................... 17
FUEL HEATER......................... 17
FUEL INJECTION PUMP................. 19
FUEL INJECTORS...................... 22
FUEL LEVEL SENSOR................... 18
FUEL RESERVOIR MODULE.............. 25
FUEL SHUTDOWN SOLENOID............ 23
FUEL TANK........................... 23
HIGH-PRESSURE LINES................. 26
SPECIFICATIONS
FUEL INJECTOR FIRING SEQUENCE....... 27
FUEL SYSTEM PRESSURE............... 27
FUEL TANK CAPACITY.................. 27
IDLE SPEED.......................... 27
DESCRIPTION AND OPERATION
INTRODUCTION
This Fuel Delivery section will cover components
not controlled by the PCM. For components con-
trolled by the PCM, refer to the Fuel Injection Sys-
temÐ2.5L Diesel Engine section of this group.
The fuel heater relay, fuel heater and fuel gauge
are not operated by the PCM. These components are
controlled by the ignition (key) switch. All other fuel
system electrical components necessary to operate
the engine are controlled or regulated by the PCM.
FUEL SYSTEM PRESSURE WARNING
WARNING: HIGH±PRESSURE FUEL LINES DELIVER
DIESEL FUEL UNDER EXTREME PRESSURE FROM
THE INJECTION PUMP TO THE FUEL INJECTORS.
THIS MAY BE AS HIGH AS 45,000 KPA (6526 PSI).
USE EXTREME CAUTION WHEN INSPECTING FORHIGH±PRESSURE FUEL LEAKS. INSPECT FOR
HIGH±PRESSURE FUEL LEAKS WITH A SHEET OF
CARDBOARD (Fig. 1). HIGH FUEL INJECTION
PRESSURE CAN CAUSE PERSONAL INJURY IF
CONTACT IS MADE WITH THE SKIN.
FUEL TANK
The fuel tank and tank mounting used with the
diesel powered engine is the same as used with gas-
oline powered models, although the fuel tank module
is different.
The fuel tank contains the fuel tank module and
two rollover valves. Two fuel lines are routed to the
fuel tank module. One line is used for fuel supply to
the fuel filter/water separator. The other is used to
return excess fuel back to the fuel tank.
The fuel tank module contains the fuel gauge elec-
trical sending unit.An electrical fuel pump is not
used with the diesel engine.
NS/GSFUEL SYSTEMÐ2.5L DIESEL ENGINE/2.0L GAS ENGINE 14 - 3
FUEL TANK MODULE
An electric fuel pump is not attached to the fuel
tank module for diesel powered engines. Fuel is sup-
plied by the fuel injection pump.
The fuel tank module is installed in the top of the
fuel tank (Fig. 2). The fuel tank module contains the
following components:
²Fuel reservoir
²A separate in-tank fuel filter
²Electric fuel gauge sending unit
²Fuel supply line connection
²Fuel return line connection
FUEL GAUGE SENDING UNIT
The fuel gauge sending unit is attached to the side
of the fuel pump module. The sending unit consists of
a float, an arm, and a variable resistor (track). The
track is used to send an electrical signal used for fuel
gauge operation.
As the fuel level increases, the float and arm move
up. This decreases the sending unit resistance, caus-
ing the fuel gauge on the instrument panel to read
full. As the fuel level decreases, the float and arm
move down. This increases the sending unit resis-
tance, causing the fuel gauge on the instrument
panel to read empty.
FUEL FILTER/WATER SEPARATOR
The fuel filter/water separator assembly is located
in the engine compartment near the strut tower (Fig.
3).
The combination fuel filter/water separator pro-
tects the fuel injection pump by helping to remove
water and contaminants from the fuel. Moisture col-
lects at the bottom of the filter/separator in a plastic
bowl.
The fuel filter/water separator assembly contains
the fuel filter, fuel heater element, and fuel drain
valve.
For information on the fuel heater, refer to Fuel
Heater in this group.
Refer to the maintenance schedules in Group 0 in
this manual for the recommended fuel filter replace-
ment intervals.
Fig. 1 Typical Fuel Pressure Test at Injector
Fig. 2 Fuel Tank
Fig. 3 Fuel Filter/Water Separator Location
14 - 4 FUEL SYSTEMÐ2.5L DIESEL ENGINE/2.0L GAS ENGINENS/GS
DESCRIPTION AND OPERATION (Continued)
For periodic draining of water from the bowl, refer
to Fuel Filter/Water Separator Removal/Installation
in this group.
FUEL SHUTDOWN SOLENOID
The fuel shutdown solenoid is controlled and
operated by the PCM.
The fuel shutdown (shut-off) solenoid is used to
electrically shut off the diesel fuel supply to the high-
pressure fuel injection pump. The solenoid is
mounted to the rear of the injection pump (Fig. 4).
The solenoid controls starting and stopping of the
engine regardless of the position of the accelerator
pedal. When the ignition (key) switch is OFF, the
solenoid is shut off and fuel flow is not allowed to the
fuel injection pump. When the key is placed in the
ON or START positions, fuel supply is allowed at the
injection pump.
FUEL INJECTION PUMP
The fuel injection pump is a mechanical distribu-
tor±type, Bosch VP36 series (Fig. 5). A gear on the
end of the injection pump shaft meshes with the
drive gear at the front of engine. The pump is
mechanically timed, relative to the position of the
cam and crankshaft. The PCM can make adjust-
ments to the timing of the injection pump.
The injection pump contains the fuel shutdown
solenoid, fuel temperature sensor, control sleeve sen-
sor, fuel quantity actuator and the fuel timing sole-
noid (Fig. 5).In the electronically controlled injection pump, the
pump plunger works the same as the pump plunger
in a mechanically controlled injection pump, but the
amount of fuel and the time the fuel is injected is
controlled by the vehicle's PCM, instead of by a
mechanical governor assembly. A solenoid controlled
by the PCM is used in place of the mechanical gov-
ernor assembly, and it moves a control sleeve inside
the pump that regulates the amount of fuel being
injected. There is no mechanical connection between
the accelerator pedal and the electronically controlled
injection pump. Instead, a sensor connected to the
accelerator pedal sends a signal to the PCM that rep-
resents the actual position of the accelerator pedal.
The PCM uses this input, along with input from
other sensors to move the control sleeve to deliver
the appropriate amount of fuel. This system is known
as ªDrive-By-Wireº
The actual time that the fuel is delivered is very
important to the diesel combustion process. The PCM
monitors outputs from the engine speed sensor (fly-
wheel position in degrees), and the fuel injector sen-
sor (mechanical movement within the #1 cylinder
fuel injector). Outputs from the Accelerator Pedal
Position sensor, engine speed sensor (engine rpm)
and engine coolant temperature sensor are also used.
The PCM will then compare its set values to these
outputs to electrically adjust the amount of fuel tim-
ing (amount of advance) within the injection pump.
This is referred to as ªClosed Loopº operation. The
PCM monitors fuel timing by comparing its set value
to when the injector #1 opens. If the value is greater
than a preset value a fault will be set.
Fig. 4 Fuel Shutdown Solenoid and Overflow Valve
Location
Fig. 5 Fuel Injection Pump
NS/GSFUEL SYSTEMÐ2.5L DIESEL ENGINE/2.0L GAS ENGINE 14 - 5
DESCRIPTION AND OPERATION (Continued)
Actual electric fuel timing (amount of advance) is
accomplished by the fuel timing solenoid mounted to
the bottom of the injection pump (Fig. 5). Fuel timing
will be adjusted by the PCM, which controls the fuel
timing solenoid.
An overflow valve is attached into the fuel return
line at the rear of the fuel injection pump (Fig. 4).
This valve serves two purposes. One is to ensure that
a certain amount of residual pressure is maintained
within the pump when the engine is switched off.
This will prevent the fuel timing mechanism within
the injection pump from returning to its zero posi-
tion. The other purpose is to allow excess fuel to be
returned to the fuel tank through the fuel return
line. The pressure values within this valve are preset
and can not be adjusted.
The fuel injection pump supplies high±pressure
fuel of approximately 45,000 kPa (6526 psi) to each
injector in precise metered amounts at the correct
time.
For mechanical injection pump timing, refer to
Fuel Injection Pump Timing in the Service Proce-
dures section of this group.
FUEL INJECTORS
Fuel drain tubes (Fig. 6) are used to route excess
fuel back to the overflow valve (Fig. 4) at the rear of
the injection pump. This excess fuel is then returned
to the fuel tank through the fuel return line.
The injectors are connected to the fuel injection
pump by the high± pressure fuel lines. A separate
injector is used for each of the four cylinders. An
injector containing a sensor (Fig. 7) is used on thecylinder number one injector. This injector is called
instrumented injector #1 or needle movement sensor.
It is used to tell the PCM when the #1 injector's
internal spring-loaded valve seat has been forced
open by pressurized fuel being delivered to the cylin-
der, which is at the end of its compression stroke.
When the instrumented injector's valve seat is force
open, it sends a small voltage spike pulse to the
PCM. This tells the PCM that the engine is at TDC
on the number one cylinder. It is not used with the
other three injectors.
Fuel enters the injector at the fuel inlet (top of
injector) and is routed to the needle valve bore. When
fuel pressure rises to approximately 15,000±15,800
kPa (2175±2291 psi), the needle valve spring tension
is overcome. The needle valve rises and fuel flows
through the spray holes in the nozzle tip into the
combustion chamber. The pressure required to lift
the needle valve is the injector opening pressure set-
ting. This is referred to as the ªpop-offº pressure set-
ting.
Fuel pressure in the injector circuit decreases after
injection. The injector needle valve is immediately
closed by the needle valve spring and fuel flow into
the combustion chamber is stopped. Exhaust gases
are prevented from entering the injector nozzle by
the needle valve.
A copper washer (gasket) is used at the base of
each injector (Fig. 7) to prevent combustion gases
from escaping.
Fuel injector firing sequence is 1±3±4±2.
FUEL TUBES/LINES/HOSES AND CLAMPSÐLOW-
PRESSURE TYPE
Also refer to the proceeding section on Quick±Con-
nect Fittings.
Inspect all hose connections such as clamps, cou-
plings and fittings to make sure they are secure andFig. 6 Fuel Injectors and Drain Tubes
Fig. 7 Fuel Injector Sensor
14 - 6 FUEL SYSTEMÐ2.5L DIESEL ENGINE/2.0L GAS ENGINENS/GS
DESCRIPTION AND OPERATION (Continued)
leaks are not present. The component should be
replaced immediately if there is any evidence of deg-
radation that could result in failure.
Never attempt to repair a plastic fuel line/tube or a
quick±connect fitting. Replace complete line/tube as
necessary.
Avoid contact of any fuel tubes/hoses with other
vehicle components that could cause abrasions or
scuffing. Be sure that the fuel lines/tubes are prop-
erly routed to prevent pinching and to avoid heat
sources.
The lines/tubes/hoses are of a special construction.
If it is necessary to replace these lines/tubes/hoses,
use only original equipment type.
The hose clamps used to secure the rubber hoses
are of a special rolled edge construction. This con-
struction is used to prevent the edge of the clamp
from cutting into the hose. Only these rolled edge
type clamps may be used in this system. All other
types of clamps may cut into the hoses and cause
fuel leaks.
Where a rubber hose is joined to a metal tube
(staked), do not attempt to repair. Replace entire
line/tube assembly.
Use new original equipment type hose clamps.
Tighten hose clamps to 2 N´m (20 in. lbs.) torque.
QUICK-CONNECT FITTINGSÐLOW PRESSURE
TYPE
Different types of quick-connect fittings are used to
attach various fuel system components. These are: a
single-tab type, a two-tab type or a plastic retainer
ring type (Fig. 8). Refer to Quick-Connect Fittings in
the Removal/Installation section for more informa-
tion.
CAUTION: The interior components (o-rings, spac-
ers) of quick-connect fitting are not serviced sepa-
rately, but new pull tabs are available for some
types. Do not attempt to repair damaged fittings or
fuel lines/tubes. If repair is necessary, replace the
complete fuel tube assembly.
HIGH-PRESSURE FUEL LINES
CAUTION: The high±pressure fuel lines must be
held securely in place in their holders. The lines
cannot contact each other or other components. Do
not attempt to weld high±pressure fuel lines or to
repair lines that are damaged. Only use the recom-
mended lines when replacement of high±pressure
fuel line is necessary.
High±pressure fuel lines deliver fuel under pres-
sure of up to approximately 45,000 kPa (6526 PSI)
from the injection pump to the fuel injectors. Thelines expand and contract from the high±pressure
fuel pulses generated during the injection process. All
high±pressure fuel lines are of the same length and
inside diameter. Correct high±pressure fuel line
usage and installation is critical to smooth engine
operation.
WARNING: USE EXTREME CAUTION WHEN
INSPECTING FOR HIGH±PRESSURE FUEL LEAKS.
INSPECT FOR HIGH±PRESSURE FUEL LEAKS WITH
A SHEET OF CARDBOARD. HIGH FUEL INJECTION
PRESSURE CAN CAUSE PERSONAL INJURY IF
CONTACT IS MADE WITH THE SKIN.
FUEL DRAIN TUBES
These rubber tubes are low±pressure type.
Some excess fuel is continually vented from the
fuel injection pump. During injection, a small amount
of fuel flows past the injector nozzle and is not
injected into the combustion chamber. This fuel
drains into the fuel drain tubes (Fig. 9) and back to
the tee banjo fitting, which is connected to the same
line as the overflow valve, which allows a variable
quantity to return to the fuel tank. The overflow
valve is calibrated to open at a preset pressure.
Excess fuel not required by the pump to maintain the
minimum pump cavity pressure is then returned
through the overflow valve and on to the fuel tank
through the fuel return line.
Fig. 8 Plastic Retainer Ring-Type Fitting
NS/GSFUEL SYSTEMÐ2.5L DIESEL ENGINE/2.0L GAS ENGINE 14 - 7
DESCRIPTION AND OPERATION (Continued)