EXHAUST SYSTEM
TABLE OF CONTENTS
page page
EXHAUST SYSTEM
DESCRIPTION............................1
OPERATION.............................1
DIAGNOSIS AND TESTING..................2
EXHAUST SYSTEM......................2
EXHAUST SYSTEM RESTRICTION CHECK....2
INSPECTION.............................3
ADJUSTMENTS...........................3
SPECIFICATIONS.........................3
CATALYTIC CONVERTER
DESCRIPTION............................4
OPERATION.............................4
REMOVAL...............................4
INSPECTION.............................5
INSTALLATION............................5CROSS-OVER PIPE
REMOVAL...............................6
INSTALLATION............................6
HEAT SHIELDS
DESCRIPTION............................6
OPERATION.............................6
REMOVAL...............................7
INSTALLATION............................7
MUFFLER
REMOVAL...............................7
INSTALLATION............................7
RESONATOR
REMOVAL...............................8
INSTALLATION............................8
EXHAUST SYSTEM
DESCRIPTION
The exhaust system consist of a catalytic converter,
muffler, and a resonator with connecting pipes in-be-
tween (Fig. 1). The system is serviced in two sections;
the catalytic converter and pipe, and the muffler and
resonator with connecting pipe. A band clamp is used
to connect the joint between the two components.
Three support hanger rods with rubber isolators areused to support and isolate the exhaust system. A
flexible joint, integral to the catalytic converter,
allows for engine movement. On vehicles equipped
with AWD, an additional heat shield is mounted to
the catalytic converter. The exhaust system is tuned
for each vehicle/powertrain combination.
OPERATION
The exhaust system contains, quiets, and cleans
the exhaust gases generated by the engine.
Fig. 1 Exhaust System - Typical (All Vehicles)
1 - CATALYTIC CONVERTER
2 - BAND CLAMP
3 - SUPPORTS - MUFFLER
4 - SUPPORT - RESONATOR5 - RESONATOR
6 - MUFFLER
RSEXHAUST SYSTEM11-1
DIAGNOSIS AND TESTING - EXHAUST SYSTEM
CONDITION POSSIBLE CAUSES CORRECTION
EXCESSIVE EXHAUST NOISE
(UNDER HOOD)1. Exhaust manifold cracked or
broken.1. Replace manifold.
2. Manifold to cylinder head leak. 2. Tighten manifold and/or replace
gasket.
3. EGR Valve to manifold gasket
leakage.3. Tighten fasteners or replace
gasket.
4. EGR Valve to EGR tube gasket
leakage.4. Tighten fasteners or replace
gasket.
5. EGR tube to manifold tube
leakage.5. Tighten tube nut.
6. Exhaust flex-joint to manifold
leak.6. Tighten joint fasteners and/or
replace gasket.
7. Exhaust flex-joint. 7. Replace catalytic converter
assembly.
8. Pipe and shell noise from front
exhaust pipe.8. Characteristic of single wall pipe.
EXCESSIVE EXHAUST NOISE 1. Leak at exhaust pipe joints. 1. Tighten clamps at leaking joints.
2. Burned or rusted out muffler
assembly or exhaust pipe.2. Replace muffler resonator tailpipe
assembly or exhaust pipe with
catalytic converter assembly.
3. Burned or rusted out resonator. 3. Replace muffler resonator tailpipe
assembly.
4. Restriction in exhaust system. 4. Perform exhaust restriction test.
replace component as necessary.
5. Converter material in muffler. 5. Replace muffler and converter
assemblies. Check fuel injection and
ignition systems for proper
operation.
DIAGNOSIS AND TESTING - EXHAUST SYSTEM
RESTRICTION
Exhaust system restriction can be checked by mea-
suring back pressure using the DRB IIItand PEP
module pressure tester.
WARNING: THE NORMAL OPERATING TEMPERA-
TURE OF THE EXHAUST SYSTEM IS VERY HIGH.
THEREFORE, NEVER WORK AROUND OR ATTEMPT
TO SERVICE ANY PART OF THE EXHAUST SYSTEM
UNTIL IT IS COOLED. SPECIAL CARE SHOULD BE
TAKEN WHEN WORKING NEAR THE CATALYTIC
CONVERTER. THE TEMPERATURE OF THE CON-
VERTER RISES TO A HIGH LEVEL AFTER A SHORT
PERIOD OF ENGINE OPERATION TIME.
(1) Disconnect and remove the upstream (before
catalytic converter) oxygen sensor. (Refer to 14 -FUEL SYSTEM/FUEL INJECTION/O2 SENSOR -
REMOVAL)
(2) Install the Exhaust Back Pressure Fitting
Adaptor CH8519.
(3) Connect the Low Pressure Sensor (15 psi)
CH7063 to the back pressure fitting.
(4) Following the PEP module instruction manual,
connect all required cables to the DRB IIItand PEP
module. Select the available menu options on the
DRBIIItdisplay screen for using the digital pressure
gauge function.
(5) Apply the park brake and start the engine.
(6) With transmission in Park or Neutral, raise
engine speed to 2000 RPM. Monitor the pressure
readings on the DRBIIIt. Back pressure should not
exceed specified limit. Refer to specification in table
below EXHAUST BACK PRESSURE LIMITS .
11 - 2 EXHAUST SYSTEMRS
EXHAUST SYSTEM (Continued)
(3) Remove catalytic converter to exhaust manifold
attaching fasteners (Fig. 5).
(4) Remove catalytic converter and gasket (Fig. 5).
INSPECTION
WARNING: THE NORMAL OPERATING TEMPERA-
TURE OF THE EXHAUST SYSTEM IS VERY HIGH.
THEREFORE, NEVER ATTEMPT TO SERVICE ANY
PART OF THE EXHAUST SYSTEM UNTIL IT IS
COOLED. SPECIAL CARE SHOULD BE TAKEN
WHEN WORKING NEAR THE CATALYTIC CON-
VERTER. THE TEMPERATURE OF THE CONVERTER
RISES TO A HIGH LEVEL AFTER A SHORT PERIOD
OF ENGINE OPERATION TIME.
Check catalytic converter for a flow restriction.
(Refer to 11 - EXHAUST SYSTEM - DIAGNOSIS
AND TESTING) Exhaust System Restriction Check
for procedure.
Visually inspect the catalytic converter element by
using a borescope or equivalent. Remove both oxygen
sensors and insert borescope. If borescope is not
available, remove converter and inspect element
using a flashlight. Inspect element for cracked or
melted substrate.
NOTE: Before replacing a catalytic converter, deter-
mine the root cause of failure. Most catalytic con-
verter failures are caused by air, fuel or ignition
problems. (Refer to Appropriate Diagnostic Informa-
tion) for test procedures.
INSTALLATION
(1) Position new gasket onto the manifold flange
and install catalytic converter (Fig. 5). Tighten fas-
teners to 37 N´m (325 in. lbs.).
NOTE: Be careful not to twist or kink the oxygen
sensor wires.
(2) Install (if removed) and connect the down-
stream oxygen sensor (Fig. 4).
(3) Install the muffler/resonator assembly. (Refer
to 11 - EXHAUST SYSTEM/MUFFLER - INSTALLA-
TION)
Fig. 4 Downstream Oxygen Sensor
1 - OXYGEN SENSOR CONNECTOR
2 - CATALYTIC CONVERTER
3 - DOWNSTREAM OXYGEN SENSOR
4 - ENGINE HARNESS CONNECTOR
Fig. 5 Catalytic Converter to Exhaust Manifold
1 - FLAG NUT
2 - GASKET
3 - BOLT
4 - CATALYTIC CONVERTER
RSEXHAUST SYSTEM11-5
CATALYTIC CONVERTER (Continued)
The fuel filter is replaceable, it is mounted on the
outside and on top of the fuel tank. Refer to the
Maintenance Schedules in the Introduction section of
this manual for recommended fuel filter replacement
intervals.
FFV REPLACEMENT PARTS
Many components in a Flexible Fuel Vehicle (FFV)
are designed to be compatible with ethanol. Always
be sure that the vehicle is serviced with correct etha-
nol compatible parts.
CAUTION: Replacing fuel system components with
non-ethanol compatible components can damage
your vehicle and may void the warranty.
OPERATION
The fuel system is provided fuel pressure by an in-
tank pump module. The PCM controls the operation
of the fuel system by providing battery voltage to the
fuel pump through the fuel pump relay. The PCM
requires only three inputs and a good ground to oper-
ate the fuel pump relay. The three inputs are:
²Ignition voltage
²Crankshaft Position (CKP) sensor
²Camshaft Position (CMP) sensor
DIAGNOSIS AND TESTING - FUEL DELIVERY
SYSTEM
(Refer to Appropriate Diagnositic Information)
STANDARD PROCEDURE - FUEL SYSTEM
PRESSURE RELEASE PROCEDURE
(1) Remove Fuel Pump relay from Power Distribu-
tion Center (PDC). For location of relay, refer to label
on underside of PDC cover.(2) Start and run engine until it stalls.
(3) Attempt restarting engine until it will no
longer run.
(4) Turn ignition key to OFF position.
(5) Place a rag or towel below fuel line quick-con-
nect fitting at fuel rail.
(6) Return fuel pump relay to PDC.
(7) One or more Diagnostic Trouble Codes (DTC's)
may have been stored in PCM memory due to fuel
pump relay removal. The DRB IIItscan tool must be
used to erase a DTC.
STANDARD PROCEDURE - DRAINING FUEL
TANK
(1) Release fuel system pressure, refer to the Fuel
System Release Procedure in this section.
(2) Insert a 1/4 inch siphon (max. O. D. 5/16) hose
from a portable fuel siphoning tank through the fuel
filler neck opening into the fuel tank. Hose most
have a 30 degree angle cut on the end to bypass the
check valve in the end of the filler neck. Refer to the
siphoning tank's Manufacturing Instructions.
(3) Drain fuel from fuel tank into siphoning tank.
SPECIFICATIONS
FUEL SYSTEM PRESSURE
400 kpa634 kpa (58 psi65 psi)
TORQUE
DESCRIPTION N´m Ft. Lbs. In. Lbs.
Fuel Rail 2.4L 22 200
Fuel Rail 3.3/3.8L 11.8 105
Fuel Tank Strap 54 40
Fuel Tank T Strap 28.2 250
Fuel Filter Bolt 4.5 40
14 - 2 FUEL DELIVERYRS
FUEL DELIVERY (Continued)
The pressure regulator is a mechanical device that
is NOT controlled by the PCM or engine vacuum.
REMOVAL
The fuel pressure regulator is part of the fuel
pump module (Fig. 9). Remove the fuel pump module
from the fuel tank to access the fuel pressure regula-
tor. Refer to the Fuel Pump Module removal in this
section.
(1) Spread tangs on pressure regulator retainer.
(2) Pry fuel pressure regulator out of housing.
(3) Ensure both upper and lower O-rings were
removed with regulator.
INSTALLATION
The fuel pressure regulator is part of the fuel
pump module. Remove the fuel pump module from
the fuel tank to access the fuel pressure regulator.
Refer to the Fuel Pump Module removal in this sec-
tion.
(1)
Lightly lubricate the O-rings with clean engine oil
and place them into opening in pump module (Fig. 9).
(2) Push regulator into opening in pump module.
(3) Fold tangs on regulator retainer over tabs on
housing.
FUEL PUMP
DESCRIPTION
The electric fuel pump is located in and is part of
the fuel pump module. It is a positive displacement,
gerotor type, immersible pump with a permanent
magnet electric motor. The fuel pump module is sus-
pended in fuel in the fuel tank.
OPERATION
The pump draws fuel through a strainer and
pushes it through the motor to the outlet. The pump
contains a check valve. The valve, in the pump out-
let, maintains pump pressure during engine off con-
ditions. The fuel pump relay provides voltage to the
fuel pump. The fuel pump has a maximum dead-
headed pressure output of approximately 880 kPa
(130 psi). The regulator adjusts fuel system pressure
to approximately 400 kpa634 kpa (58 psi65 psi).
FUEL PUMP MODULE
DESCRIPTION
The fuel pump module is installed in the top of the
fuel tank (Fig. 10).
The fuel pump module contains the following:
²Electric fuel pump
²Fuel pump reservoir
²Inlet strainer
²Fuel pressure regulator
²Fuel gauge sending unit
²Fuel supply line connection
The inlet strainer, fuel pressure regulator
and fuel level sensor are the only serviceable
items. If the fuel pump or electrical wiring har-
ness requires service, replace the fuel pump
module.
The electric fuel pump is located in and is part of
the fuel pump module. It is a positive displacement,
gerotor type, immersible pump with a permanent
magnet electric motor.
OPERATION
The pump draws fuel through a strainer and
pushes it through the motor to the outlet. The pump
contains one check valve. The check valve, in the
Fig. 9 Fuel Pressure Regulator O-rings
1 - UPPER O-RING
2 - LOWER 0-RING
Fig. 10 Fuel Pump Module
1 - INLET STRAINER
2 - FUEL RESERVOIR
3 - FUEL PRESSURE REGULATOR
4 - FUEL LEVEL SENSOR
RSFUEL DELIVERY14-7
FUEL PRESSURE REGULATOR (Continued)
pump outlet, maintains pump pressure during engine
off conditions. The fuel pump relay provides voltage
to the fuel pump.
The fuel pump has a maximum deadheaded pres-
sure output of approximately 880 kPa (130 psi). The
regulator adjusts fuel system pressure to approxi-
mately 400634 kPa (5865 psi).
FUEL PUMP ELECTRICAL CONTROL
Voltage to operate the electric pump is supplied
through the fuel pump relay. For an electrical opera-
tional description of the fuel pump refer to fuel Pump
RelayÐPCM Output.
ELECTRICAL PUMP REPLACEMENT
The electric fuel pump is not serviceable. If the
fuel pump or electrical wiring harness needs replace-
ment, the complete fuel pump module must be
replaced. Perform the Fuel System Pressure Release
procedure before servicing the fuel pump.
REMOVAL
WARNING: RELEASE FUEL SYSTEM PRESSURE
BEFORE SERVICING FUEL SYSTEM COMPONENTS.
SERVICE VEHICLES IN WELL VENTILATED AREAS
AND AVOID IGNITION SOURCES. NEVER SMOKE
WHILE SERVICING THE VEHICLE.
(1) Remove fuel filler cap and perform Fuel Sys-
tem Pressure Release procedure.
(2) Disconnect negative cable from auxiliary
jumper terminal.
(3) Drain fuel tank, refer to the Fuel Tank proce-
dure in the Fuel Delivery section.
(4) Remove fuel tank, refer to the Fuel Tank
removal section.
(5) Clean top of tank to remove loose dirt and
debris.
(6) Using a brass punch and hammer remove lock-
nut to release pump module (Fig. 11).
WARNING: THE FUEL RESERVOIR OF THE FUEL
PUMP MODULE DOES NOT EMPTY OUT WHEN THE
TANK IS DRAINED. THE FUEL IN THE RESERVOIR
MAY SPILL OUT WHEN THE MODULE IS REMOVED.
(7) Remove fuel pump module and O-ring from
tank (Fig. 12). Discard O-ring.
INSTALLATION
(1) Wipe seal area of tank clean and place a new
O-ring seal in position on pump.
(2) Position fuel pump module in tank.
(3) Tighten locknut using a brass punch and ham-
mer to install the locknut (Fig. 11).
(4) Install fuel tank, refer to the Fuel Tank instal-
lation section.(5) Lower vehicle.
(6) Connect negative cable battery.
(7) Fill fuel tank. Check for leaks.
(8) Install fuel filler cap.
Fig. 11 FUEL PUMP MODULE LOCKING RING
Fig. 12 Fuel Pump Module Removal
1 - FUEL PUMP MODULE
2 - O-RING
14 - 8 FUEL DELIVERYRS
FUEL PUMP MODULE (Continued)
FUEL RAIL
REMOVAL - 2.4L
(1) Perform fuel system pressure release procedure
before servicing or starting repairs.Refer to
Fuel System Pressure Release Procedure in this sec-
tion.
(2) Disconnect negative cable from battery.
(3) Disconnect the wiring connectors for fuel injec-
tors harness (Fig. 13).
(4) Remove wiring harness from brackets.
(5) Disconnect the connectors from the fuel injec-
tors.
(6) Remove harness from vehicle.
(7) Remove fuel hose quick connect fitting from the
chassis tube.Refer to Fuel Hoses, Clamps and
Quick Connect Fittings in this Section.Place a
shop towel under the connections to absorb any fuel
spilled from the fitting.
WARNING: WRAP A SHOP TOWEL AROUND HOSES
TO CATCH ANY GASOLINE SPILLAGE.
(8) Remove fuel rail attaching bolts.
(9) Remove fuel rail. Be careful not to damage the
injector O-rings upon removal from their ports.
REMOVAL - 3.3/3.8L
(1) Perform fuel system pressure release procedure
before servicing or starting repairs.Refer to
Fuel System Pressure Release Procedure in this sec-
tion.
(2) Disconnect negative cable from battery.
(3) Remove upper intake manifold, refer to the
Engine/Manifolds/Upper Intake for more informa-
tion..
(4) Cover intake manifold with suitable cover
when servicing.(5) Remove the fuel hose quick connect fitting from
the chassis tube.Refer to Fuel Hoses, Clamps
and Quick Connect Fittings in this Section.
WARNING: WRAP A SHOP TOWEL AROUND HOSES
TO CATCH ANY GASOLINE SPILLAGE.
(6) Remove the fuel rail attaching bolts (Fig. 14).
(7) Remove fuel rail. Be careful not to damage the
injector O-rings upon removal from their ports.
INSTALLATION - 2.4L
(1) Ensure injector holes are clean. Replace
O-rings if damaged.
(2) Lubricate injector O-rings with a drop of clean
engine oil to ease installation.
(3) Put the tip of each injector into their ports.
Push the assembly into place until the injectors are
seated in the ports.
(4) Install the fuel rail mounting bolts. Tighten
bolts to 22 N´m (200 in. lbs.) torque.
(5) Connect the connectors to the fuel injectors.
(6) Install wiring harness to brackets.
(7) Connect the wiring connectors to fuel injectors
harness (Fig. 13).
(8) Connect negative battery cable.
(9) Use the DRBIIItscan tool to pressurize the
fuel system. Check for leaks.
INSTALLATION - 3.3/3.8L
(1) Ensure injector holes are clean. Replace
O-rings if damaged.
(2) Lubricate injector O-rings with a drop of clean
engine oil to ease installation.
Fig. 13 FUEL RAIL AND INJECTORS 2.4L
1 - Fuel Injectors
2 - Fuel Rail
Fig. 14 FUEL INJECTORS 3.3/3.8L
1 - FUEL INJECTORS
RSFUEL DELIVERY14-9
(3) Put the tip of each injector into their ports.
Push the assembly into place until the injectors are
seated in the ports.
(4) Install the fuel rail mounting bolts. Tighten
bolts to 22 N´m (200 in. lbs.) torque.
(5) Remove covering on lower intake manifold and
clean surface.
(6) Install the Upper Intake Manifold, refer to
Engine/Manifolds/Upper Intake for more information.
(7) Install fuel hose quick connector fitting to chas-
sis tubes.Refer to Fuel Hoses, Clamps and
Quick Connect Fittings in this Section.Push the
fitting onto the chassis tube until it clicks into place.
Pull on the fitting to ensure complete insertion.
(8) Connect negative cable to battery.
(9) Use the DRBIIItscan tool to pressurize the
fuel system. 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. The tank is made
from High density Polyethylene (HDPE) material.If
equipped with ORVR (Onboard Refueling Vapor
Recovery) it has been added to the fuel tank to con-
trol refueling vapor emissions.
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.
All models are equipped with either one or two
rollover valves mounted into the top of the fuel tank
(or pump module).
An evaporation control system is connected to the
rollover valve(s)/control valves(Refer to 25 - EMIS-
SIONS CONTROL/EVAPORATIVE EMISSIONS/
ORVR - OPERATION) 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 tempo-
rarily held. When the engine is running, the vapors
are drawn into the intake manifold. In addition, fuel
vapors produced during vehicle refueling are allowed
to pass through the vent hoses/tubes to the charcoal
canister(s) for temporary storage (prior to being
drawn into the intake manifold). All models areequipped with a self-diagnosing system using a Leak
Detection Pump (LDP). Refer to the Emission Control
System for additional information.
INLET CHECK VALVE
All vehicles have an inlet check valve on the inside
of the fuel tank at the filler inlet
The valve prevents fuel from splashing back on
customer during vehicle refueling. The valve is a
non-serviceable item.
REMOVAL
(1) Remove fuel filler cap and perform Fuel Sys-
tem Pressure Release procedure.
(2) Disconnect negative cable from battery.
(3) Insert fuel siphon hose into fuel filler neck and
push it into the tank.
(4) Drain fuel tank dry into holding tank or a
properly labeledGASOLINEsafety container.
(5) Raise vehicle on hoist and support.
(6) Use a transmission jack to support fuel tank.
Remove bolts from fuel tank straps.
(7) Lower tank slightly.
Fig. 15 Fuel Tank
1 - ROLLOVER VALVE
2 - FUEL FILLER INLET
3 - ROLLOVER VALVE
4 - GROUND STRAP
5 - FUEL FILTER
6 - FUEL PUMP MODULE
14 - 10 FUEL DELIVERYRS
FUEL RAIL (Continued)