1993 CHEVROLET DYNASTY service

(4) Remove throttle cable (Fig. 3). Remove wiring
harness from throttle cable bracket.
(5) Remove automatic idle speed (AIS) motor and
throttle position sensor (TPS) wiring connectors from
throttle body (Fig. 4). (e) Remove jumper wires.
(f) Continue fuel system service.
(6) Remove vacuum hose harness from throttle
body (Fig. 4). (7) Remove PCV and brake booster hoses from air
intake plenum (Fig. 5). (8) Remove EGR tube flange from intake plenum
(Fig. 5). (9) Disconnect Charge Temperature Sensor electri-
cal connector. Remove vacuum harness connectors
from Intake Plenum (Fig. 5).
(10) Remove cylinder head to intake plenum strut
(Fig. 5). (11) Disconnect MAP Sensor and heated Oxygen
Sensor electrical connection. Remove the engine
mounted ground strap (Fig. 6).
Fig. 3 Throttle Cable Attachment
Fig. 4 Electrical and Vacuum Connection to Throttle Body
Fig. 5 Electrical and Vacuum Connections To IntakeManifold
Fig. 6 MAP Sensor Electrical Connector
11 - 20 EXHAUST SYSTEM AND INTAKE MANIFOLD Ä

FUEL SYSTEMS
CONTENTS
page page
2.2L TURBO III MULTI-PORT FUEL INJECTIONÐ GENERAL DIAGNOSIS ................. 95
2.2L TURBO III MULTI-PORT FUEL INJECTIONÐ ON-BOARD DIAGNOSTICS ............. 100
2.2L TURBO III MULTI-PORT FUEL INJECTIONÐ SERVICE PROCEDURES ............... 107
2.2L TURBO III MULTI-PORT FUEL INJECTIONÐ SYSTEM OPERATION .................. 83
2.2L/2.5L SINGLE POINT FUEL INJECTIONÐ GENERAL DIAGNOSIS .................. 35
2.2L/2.5L SINGLE POINT FUEL INJECTIONÐ ON-BOARD DIAGNOSTICS .............. 41
2.2L/2.5L SINGLE POINT FUEL INJECTIONÐ SERVICE PROCEDURES ................ 48
2.2L/2.5L SINGLE POINT FUEL INJECTIONÐ SYSTEM OPERATION .................. 24
2.5L FLEXIBLE FUEL MULTI-PORT FUEL INJECTIONÐGENERAL DIAGNOSIS ....... 66
2.5L FLEXIBLE FUEL MULTI-PORT FUEL INJECTIONÐON-BOARD DIAGNOSTICS . . . 70
2.5L FLEXIBLE FUEL MULTI-PORT FUEL INJECTIONÐSERVICE PROCEDURES ..... 77
2.5L FLEXIBLE FUEL MULTI-PORT FUEL INJECTIONÐSYSTEM OPERATION ....... 55 3.0L MULTI-PORT FUEL INJECTIONÐ
GENERAL DIAGNOSIS ................. 125
3.0L MULTI-PORT FUEL INJECTIONÐ ON-BOARD DIAGNOSTICS ............. 130
3.0L MULTI-PORT FUEL INJECTIONÐ SERVICE PROCEDURES ............... 138
3.0L MULTI-PORT FUEL INJECTIONÐ SYSTEM OPERATION ................. 113
3.3L AND 3.8L MULTI-PORT FUEL INJECTIONÐ GENERAL DIAGNOSIS ................. 157
3.3L AND 3.8L MULTI-PORT FUEL INJECTIONÐ ON-BOARD DIAGNOSTICS ............. 162
3.3L AND 3.8L MULTI-PORT FUEL INJECTIONÐ SERVICE PROCEDURES ............... 169
3.3L AND 3.8L MULTI-PORT FUEL INJECTIONÐ SYSTEM OPERATION ................. 145
ACCELERATOR PEDAL AND THROTTLE CABLE .............................. 21
FUEL DELIVERY SYSTEM ................. 3
FUEL TANKS .......................... 14
GENERAL INFORMATION .................. 1
SPECIFICATIONS ...................... 178
GENERAL INFORMATION
Throughout this group, references are made to a
particular vehicle by letter designation. A chart
showing the breakdown of these designations is in-
cluded in the Introduction Section at the front of this
service manual. The Fuel System consists of the fuel tank, fuel
pump, fuel filter, throttle body, fuel injectors, fuel
tubes and vacuum tubes. The Fuel Delivery System consists of the fuel
pump, fuel filter, fuel lines and fuel hoses. The Fuel Tank Assembly consists of the fuel tank,
filler tube, a fuel gauge sending unit assembly and a
pressure-vacuum filler cap. Also, the Evaporation Control System is part of the
fuel system. The evaporation control system is de-
signed to reduce the emission of fuel vapor into the
atmosphere. The description and function of the Evaporation
Control System is found in Group 25 of this manual.FUEL REQUIREMENTS
Your vehicle was designed to meet all emission
regulations and provide excellent fuel economy when
using high quality unleaded gasoline.
VEHICLES WITHOUT TURBOCHARGED ENGINES
Use unleaded gasoline having a minimum octane
rating of 87.
VEHICLES WITH TURBOCHARGED ENGINESÐEXCEPT 16 VALVE 2.2L ENGINES
These vehicles will operate satisfactorily on both
regular unleaded gasoline having a minimum octane
rating or 87, and premium unleaded gasoline having
a minimum octane rating of 91. The use of premium
unleaded gasoline will improve performance.
VEHICLES WITH 2.2L 16 VALVE ENGINES
The use of premium unleaded gasoline having a
minimum octane of 91 is recommended. If premium
unleaded is not available, then unleaded gasoline
Ä FUEL SYSTEMS 14 - 1

with a minimum octane of 87 may be used. However,
the use of lower octane gasoline will result in re-
duced performance.
FLEXIBLE FUEL AA-BODY VEHICLES
These vehicles will operate on either unleaded gas-
oline with a minimum posted octane of 87 or M85
fuel. M85 fuel is a mixture of 85 percent methanol
and 15 percent unleaded gasoline. The vehicle also
will operate on mixture of M85 and unleaded gaso-
line with a minimum posted octane of 87. Do not
use 100 percent methanol in these vehicles.
THE FOLLOWING IS APPLICABLE TO ALL VEHICLES
Light spark knock at low engine speeds is not
harmful to your engine. However, continued heavy
spark knock at high speeds can cause damage and
should be reported to your dealer immediately. En-
gine damage resulting from operating with a heavy
spark knock may not be covered by the new vehicle
warranty. In addition to using unleaded gasoline with the
proper octane rating, gasolines that contain deter-
gents, corrosion and stability additives are recom-
mended. Using gasolines that have these additives
will help improve fuel economy, reduce emissions,
and maintain vehicle performance. Generally, pre-
mium unleaded gasolines contain more additive than
regular unleaded. Poor quality gasoline can cause problems such as
hard starting, stalling, and stumble. If you experi-
ence these problems, try another brand of gasoline
before considering service for the vehicle.
GASOLINE/OXYGENATE BLENDS
Some fuel suppliers blend gasoline with materials
that contain oxygen such as alcohol, MTBE (Methyl
Tertiary Butyl Ether) and ETBE (Ethyl Tertiary Bu-
tyl Ether). The type and amount of oxygenate used
in the blend is important. The following are generally used in gasoline
blends: Ethanol - (Ethyl or Grain Alcohol) properly blended, is used as a mixture of 10 percent ethanol
and 90 percent gasoline. Gasoline blended with eth-
anol may be used in your vehicle. Methanol - (Methyl or Wood Alcohol) is used in a
variety of concentrations when blended with un-
leaded gasoline. You may find fuels containing 3 per-
cent or more methanol along with other alcohols
called cosolvents. Do not use gasolines containing Methanol.
Use of methanol/gasoline blends may result in
starting and driveability problems and damage criti-
cal fuel system components. Problems that are the result of using methanol/gas-
oline blends are not the responsibility of Chrysler
Motors and may not be covered by the new vehicle
warranty. MTBE/ETBE - Gasoline and MTBE (Methyl Ter-
tiary Butyl Ether) blends are a mixture of unleaded
gasoline blended and up to 15 percent MTBE. Gaso-
line and ETBE (Ethyl Tertiary Butly Ether) are
blends of gasoline and up to 17 percent ETBE. Gas-
oline blended with MTBE or ETBE may be used in
your vehicle. Clean Air Gasoline
Many gasolines are now being blended that con-
tribute to cleaner air, especially in those areas of the
country where pollution levels are high. These new
blends provide a cleaner burning fuel and some are
referred to as reformulated gasoline. In areas of the country where carbon monoxide lev-
els are high, gasolines are being treated with oxy-
genated materials such as ETBE, MTBE and
ethanol. The use of gasoline blended with these ma-
terials also contributes to cleaner air. Chrysler Corporation supports these efforts toward
cleaner air and recommends that you use these gas-
olines as they become available. Materials Added to Fuel
Indiscriminate use of fuel system cleaning agents
should be avoided. Many of these materials intended
for gum and varnish removal may contain active sol-
vents of similar ingredients that can be harmful to
fuel system gasket and diaphragm materials.
14 - 2 FUEL SYSTEMS Ä

FUEL DELIVERY SYSTEM INDEX
page page
Chassis Fuel Tubes ...................... 11
Flexible Fuel Components ................... 3
Fuel FilterÐAll Vehicles .................... 9
Fuel Hoses, Clamps, and Quick Connect Fittings . 10
Fuel Pump Assembly ...................... 5
Fuel Pump Module Installation ............... 9
Fuel Pump Module Removal ................. 8
Fuel Pump Pressure TestÐ2.2L/2.5L TBI and 3.0L MPI Engines ........................... 7
Fuel Pump Pressure TestÐAll Except 2.2L/2.5L TBI and 3.0L MPI ....................... 6
Fuel Pump Strainer Service .................. 9 Fuel System Pressure
...................... 6
Fuel System Pressure Release ProcedureÐ 2.2L/2.5L TBI ........................... 4
Fuel System Pressure Release ProcedureÐ3.0L . . 5
Fuel System Pressure Release ProcedureÐExcept 2.2L/2.5L TBI and 3.0L ................... 4
General Information ........................ 3
Identifying Flexible Fuel Components .......... 3
Mechanical Malfunctions .................... 8
Methanol Concentration SensorÐFlexible Fuel AA-Body .............................. 4
Service Precautions for Flexible Fuel Vehicles .... 3
GENERAL INFORMATION
Beginning this model year, Chrysler began produc-
ing AA-Body vehicles designed to operate on a mix-
ture of gasoline and methanol. These automobiles are
referred to as Flexible Fuel vehicles. Flexible fuel vehicles can operate on a mixture of
up to 85 percent methanol, 15 percent unleaded gas-
oline. These vehicles also operate on mixtures con-
taining a lower percentage of methanol or just pure
unleaded gasoline. In many cases, the procedures for servicing flexible
fuel components is identical to gasoline only compo-
nents. Refer to the particular Service Procedure in
this section. If the service procedure for flexible fuel
component differs from a gasoline only component,
the title of each service procedure identifies the ap-
plication.
SERVICE PRECAUTIONS FOR FLEXIBLE FUEL
VEHICLES
Methanol is more toxic than gasoline. Always re-
lease fuel system pressure before servicing fuel sys-
tem components and wear methanol resistant gloves
and eye protection. Avoid breathing methanol vapors or ingesting
methanol. Headaches, dizziness and even uncon-
sciousness could result from breathing these vapors.
Serious injury, blindness and even death could result
from ingesting methanol. Methanol vapors are extremely flammable and can
travel along the ground. Service vehicles in well ven-
tilated areas and avoid ignition sources. Never
smoke while servicing the vehicle. Do not allow methanol to contact skin. Prolonged
contact with methanol can cause dry skin or an al-
lergic skin reaction. Also, prolonged contact could re-
sult in absorption through the skin.
IDENTIFYING FLEXIBLE FUEL COMPONENTS
Flexible Fuel vehicles have unique methanol com-
patible fuel system components. Chrysler identifies
methanol compatible components that could be phys-
ically interchanged with gasoline only parts by color-
ing them green or applying a green label or tag to
them. Even though they may appear physically iden-
tical, components for gasoline only vehicles must not
be used on flexible fuel vehicles.
FLEXIBLE FUEL COMPONENTS
Flexible fuel AA-body vehicles uses many unique
fuel system components. The unique parts are green
in appearance or have a green tag or label attached
to them. While components used on gasoline only ve-
hicles may look similar or identical, they cannot be
used on flexible fuel vehicles. When servicing a com-
ponent, always use an original equipment or equiva-
lent flexible fuel replacement. The fuel system of flexible fuel AA-body vehicles
have the following unique components.
² Fuel pump module
² Fuel level sensor
² Fuel gauge (gauge cluster).
² Fuel tank
² Fuel pressure regulator (including O-rings)
² Fuel rail
² Fuel injectors (including O-rings)
² Fuel tubes
² Fuel filter
² EVAP canister
² Fuel filler cap
² Fuel filler tube
² Pressure relief/Rollover valve
² All fuel system and emission system hoses and
tubes
Ä FUEL SYSTEMS 14 - 3

INSTRUMENT PANEL CLUSTER IDENTIFICATIONÐFLEXIBLE FUEL AA-BODY
Flexible fuel A-Body vehicles use a unique gauge
cluster. To identify the cluster, remove it from the
instrument panel and check the number on the tag
on the top. If the part number matches the number
in the parts book for flexible fuel A-bodies, the vehi-
cle was built with the correct cluster. Refer to Group
8E, Instrument Panel and Gauges, for cluster re-
moval and installation.
METHANOL CONCENTRATION SENSORÐFLEXIBLE
FUEL AA-BODY
The methanol concentration sensor contains a mi-
croprocessor that determines the percentage of gaso-
line and methanol in the fuel system. From the
methanol concentration sensor input, the powertrain
control module (PCM) determines the amount of
methanol in the fuel. The vehicle can operate on a
mixtures up to 85 percent methanol, 15 percent gas-
oline. The methanol concentration sensor output voltages
varies with the percent of methanol in the fuel sys-
tem. The sensor output voltage (input for PCM)
ranges from 0.5 volts for pure gasoline to 4.75 volts
for 85 percent methanol. For two seconds at key ON
when the operator starts the vehicle, the sensor cal-
ibrates the PCM. During the calibration period the
sensor sends 4.45 volts to the PCM as a correction
factor. The methanol concentration sensor has a built-in
shutdown capability. If the sensor shuts down, it de-
faults to the previous learned value (output voltage
based on methanol percentage of fuel). The methanol concentration sensor attaches to a
bracket at the rear of the fuel tank, next to the fuel
filler tube (Fig. 1).
REMOVAL
WARNING: RELEASE FUEL SYSTEM PRESSURE
BEFORE SERVICING FUEL SYSTEM COMPONENTS.
WHEN SERVICING FLEXIBLE FUEL VEHICLES,
WEAR METHANOL RESISTANT GLOVES AND EYE
PROTECTION AND AVOID BREATHING FUMES. DO
NOT ALLOW METHANOL/GASOLINE MIXTURES TO
CONTACT SKIN. SERVICE VEHICLES IN WELL VEN-
TILATED AREAS AND AVOID IGNITION SOURCES.
NEVER SMOKE WHILE SERVICING THE VEHICLE.
Quick connect fittings attach the fuel tubes to the
methanol concentration sensor (Fig. 1) (1) Release fuel system pressure. Refer to the Fuel
System Pressure Release Procedure. (2) Disconnect the fuel tubes from sensor. Refer to
Quick Connect Fittings in this section. (3) Disconnect electrical connector from sensor.
(4) Remove mounting nuts.
INSTALLATION
(1) Place sensor on bracket. Tighten mounting nut.
(2) Attach electrical connector to sensor.
(3) Connect fuel tubes to sensor. Refer to Quick
Connect Fittings in this section.
FUEL SYSTEM PRESSURE RELEASE
PROCEDUREÐEXCEPT 2.2L/2.5L TBI AND 3.0L
WARNING: RELEASE FUEL SYSTEM PRESSURE
BEFORE SERVICING FUEL SYSTEM COMPONENTS.
WHEN SERVICING FLEXIBLE FUEL VEHICLES,
WEAR METHANOL RESISTANT GLOVES AND EYE
PROTECTION AND AVOID BREATHING FUMES. DO
NOT ALLOW METHANOL/GASOLINE MIXTURES TO
CONTACT SKIN. SERVICE VEHICLES IN WELL VEN-
TILATED AREAS AND AVOID IGNITION SOURCES.
NEVER SMOKE WHILE SERVICING THE VEHICLE.
(1) Disconnect negative cable from battery.
(2) Remove fuel filler cap.
(3) Remove the protective cap from the fuel pres-
sure test port on the fuel rail (Fig. 2). (4) Place the open end of fuel pressure release
hose, tool number C-4799-1, into an approved gaso-
line container or a container approved for gasoline/
methanol mixtures. Connect the other end of hose
C-4799-1 to the fuel pressure test port (Fig. 3). Fuel
pressure will bleed off through the hose into the gas-
oline container. Fuel gauge C-4799-A contains hose
C-4799-1.
FUEL SYSTEM PRESSURE RELEASE
PROCEDUREÐ2.2L/2.5L TBI
CAUTION: Before servicing the fuel pump, fuel
lines, fuel filter, throttle body, or fuel injector, re-
lease fuel system pressure.Fig. 1 Methanol Concentration Sensor
14 - 4 FUEL SYSTEMS Ä

(1) Loosen fuel filler cap to release fuel tank pres-
sure. (2) Disconnect injector wiring harness connector at
edge of throttle body (Fig. 4). (3) Connect a jumper wire between terminal Num-
ber 1 of the injector harness and engine ground. (4) Connect a jumper wire to the positive terminal
Number 2 of the injector harness and touch the bat-
tery positive post for no longer than 5 seconds .
This releases system pressure. (5) Remove jumper wires.
(6) Continue fuel system service.
FUEL SYSTEM PRESSURE RELEASE
PROCEDUREÐ3.0L
(1) Disconnect the fuel rail electrical harness from
the engine harness. Refer to Group 8W, Wiring Dia-
grams. (2) Connect one end of a jumper wire to the A142
circuit terminal of the fuel rail harness connector. (3) Connect the other end of the jumper wire to a
12 volt power source. (4) Connect one end of a jumper wire to a good
ground source. (5) Momentarily ground one of the injectors by
connecting the other end of the jumper wire to an in-
jector terminal in the harness connector. Repeat pro-
cedure for 2 to 3 injectors.
FUEL PUMP ASSEMBLY
The fuel pump assembly consists of the fuel pump
and the reservoir body. The reservoir body takes the place of an internal
fuel tank reservoir. The reservoir maintains fuel at
the pump inlet during all driving conditions, espe-
cially when the fuel level is low. The system uses a positive displacement, gerotor
gear, immersible pump with a permanent magnet
electric motor (Fig. 5). The pump draws fuel through
a strainer and pushes it through the electric motor to
the outlet. The pump contains three check valves.
One valve relieves internal fuel pump pressure and
regulates maximum pump output. Another valve, in-
side the pump assembly in the fuel return circuit,
prevents fuel tank leakage if the line is damaged
during an accident. The third valve, in the pump out-
let, maintains pump pressure during engine off con-
ditions. The fuel pump relay provides voltage to the
fuel pump. All pumps have a maximum stall pres-
sure output of approximately 930 kPa (135 psi). All front wheel drive car fuel systems, except
Turbo III and flexible fuel AA-body vehicles use the
same fuel pump. Turbo III and flexible fuel AA-Body
vehicles each use different fuel pumps although they
look similar to pumps used in other vehicles. Release fuel system pressure before servicing the
fuel tank, fuel pump, fuel lines, fuel filter, or parts of
the fuel rail. Follow the Fuel System Pressure Re-
lease procedure to relieve fuel system pressure.
Fig. 2 Fuel Pressure Test PortÐTypical
Fig. 3 Releasing Fuel PressureÐEngines With Test Ports On Fuel Rail
Fig. 4 Injector Harness ConnectorÐ2.2L/2.5L TBI
Ä FUEL SYSTEMS 14 - 5

FUEL SYSTEM PRESSURE
Fuel system pressure is regulated at the fuel rail
or throttle body by a fuel pressure regulator. Refer to
the Fuel System Pressure Chart for pressure specifi-
cations. The chart reflects system pressure when the
pump is energized with the engine not running and
without vacuum applied to the pressure regulator.
FUEL PUMP PRESSURE TESTÐALL EXCEPT
2.2L/2.5L TBI AND 3.0L MPI
WARNING: RELEASE FUEL SYSTEM PRESSURE
BEFORE SERVICING FUEL SYSTEM COMPONENTS.
WHEN SERVICING FLEXIBLE FUEL VEHICLES,
WEAR METHANOL RESISTANT GLOVES AND EYE
PROTECTION AND AVOID BREATHING FUMES. DO
NOT ALLOW METHANOL/GASOLINE MIXTURES TO
CONTACT SKIN. SERVICE VEHICLES IN WELL VEN-
TILATED AREAS AND AVOID IGNITION SOURCES.
NEVER SMOKE WHILE SERVICING THE VEHICLE.
The specifications in the Fuel Pressure chart re-
flect system pressure with the vacuum hose removed
from the pressure regulator. (1) Remove the vacuum hose from the pressure
regulator before checking fuel pressure. (2) Release fuel system pressure. Refer to the Fuel
System Pressure Release procedure in this section. (3) Connect Fuel Pressure Gauge C-4799 to service
port on fuel rail (Fig. 6).
CAUTION: When using the ASD Fuel System Test,
the Auto Shutdown (ASD) Relay remains energized
for either 7 minutes, until the test is stopped, or un-
til the ignition switch is turned to the Off position.
(4) Place the ignition key in the ON position. Us-
ing the DRBII scan tool, access ASD Fuel System
Test. The ASD Fuel System Test will activate the
fuel pump and pressurize the system. If the gauge reads the specification listed in the
Fuel System Pressure chart, further testing is not re-
quired. If pressure is not correct, record the pressure
and remove gauge. Use the DRBII scan tool ASD
Fuel System Test to pressurize the system. Ensure
fuel does not leak from the fuel rail service valve. In-
stall protective cover on fuel rail service valve. If pressure is below specifications, proceed to Fuel
System Pressure Below Specifications . If pres-
sure is above specifications, proceed to Fuel System
Pressure Above Specifications .
Fuel System Pressure Below Specifications
If the fuel pressure reading in step (4) was below
specifications, test the system according to the fol-
lowing procedure.
WARNING: RELEASE FUEL SYSTEM PRESSURE
BEFORE DISCONNECTING A FUEL SYSTEM HOSE
OR COMPONENT.
(a) Perform Fuel Pressure Release procedure.
(b) Install Fuel Pressure Gauge C-4799 and Fuel
Pressure Test Adapter 6539 in the fuel supply line
between the fuel tank and fuel filter at the rear of
vehicle (Fig. 7). (c) Using the DRBII scan tool, with the ignition
key in the ON position, repeat the ASD Fuel Sys-
tem Test.
Fig. 5 Fuel PumpÐTypical
FUEL SYSTEM PRESSURE
Fig. 6 Fuel Pressure TestingÐEngines With Service Ports
14 - 6 FUEL SYSTEMS Ä

CAUTION: When using the ASD Fuel System Test,
the Auto Shutdown (ASD) Relay remains energized
for either 7 minutes, until the test is stopped, or un-
til the ignition switch is turned to the Off position.
(4) Place the ignition key in the ON position. Us-
ing the DRBII scan tool, access ASD Fuel System
Test. The ASD Fuel System Test will activate the
fuel pump and pressurize the system. If the gauge reads the pressure shown in the Fuel
System Pressure chart, further testing is not re-
quired. If pressure is not correct, record the pressure
and remove gauge. If pressure is below specifications, proceed to Fuel
System Pressure Below Specifications . If pressure
is above specifications, proceed to Fuel System
Pressure Above Specifications .
Fuel System Pressure Below Specifications
If the fuel pressure reading in step (4) was below
specifications, test the system according to the fol-
lowing procedure.
WARNING: RELEASE FUEL SYSTEM PRESSURE
BEFORE DISCONNECTING A FUEL SYSTEM HOSE
OR COMPONENT.
(a) Perform Fuel Pressure Release procedure.
(b) Install Fuel Pressure Gauge C-4799 and Fuel
Pressure Adapter 6433 in the fuel supply line (Fig.
7) between the fuel tank and fuel filter. (c) Using the DRBII scan tool, with the ignition
key in the ON position, repeat the ASD Fuel Sys-
tem Test.
² If pressure is at least 5 psi higher than reading
recorded in step (4), replace fuel filter. ² If no change is observed, gently the squeeze re-
turn hose. If fuel pressure increases, replace pressure
regulator. If the gauge reading does not change while
squeezing the return hose, the problem is either a
plugged inlet strainer or defective fuel pump. Fuel System Pressure Above Specifications If the fuel pressure reading in step (4) was above
specifications test the system according to the follow-
ing procedure.
WARNING: FUEL SYSTEM PRESSURE MUST BE
RELEASED BEFORE A FUEL SYSTEM HOSE OR
COMPONENT IS DISCONNECTED.
(a) Perform Fuel Pressure Release procedure.
(b) Install Fuel Pressure Gauge C-4799 and Fuel
Pressure Adapter 6433 in the fuel supply line be-
tween the fuel tank and fuel filter (Fig. 7). (c) Remove the fuel return line hose from the
fuel pump at fuel tank. Connect Fuel Pressure Test
Adapter 6541 to the return line (Fig. 8). Place the
other end of adapter 6541 into an approved gaso-
line container or a container approved for gasoline/
methanol mixtures (minimum 2 gallon size). All
return fuel will flow into container. (d) Using the DRBII scan tool, with the ignition
key in the ON position, repeat the ASD Fuel Sys-
tem Test.
² If pressure is now correct, replace fuel pump as-
sembly. ²
If pressure is still above specifications, remove fuel
return hose from chassis fuel tubes (at engine). Attach
Fuel Pressure Test Connect Adapter 6541 to the fuel re-
turn hose and place other end of hose in clean approved
gasoline container or a container approved for metha-
nol/gasoline mixtures (Fig. 9). Repeat test. If pressure is
now correct, check for restricted fuel return line. If no
change is observed, replace fuel pressure regulator.
MECHANICAL MALFUNCTIONS
Mechanical malfunctions are more difficult to diag-
nose with this system. The powertrain control mod-
ule (PCM) compensates for some mechanical
malfunctions. If engine performance problems are en-
countered, and no fault codes are displayed, the prob-
lem may be mechanical rather than electronic.
FUEL PUMP MODULE REMOVAL
WARNING: RELEASE FUEL SYSTEM PRESSURE
BEFORE SERVICING FUEL SYSTEM COMPONENTS.
WHEN SERVICING FLEXIBLE FUEL VEHICLES,
WEAR METHANOL RESISTANT GLOVES AND EYE
PROTECTION AND AVOID BREATHING FUMES. DO
NOT ALLOW METHANOL/GASOLINE MIXTURES TO
CONTACT SKIN. SERVICE VEHICLES IN WELL VEN-
TILATED AREAS AND AVOID IGNITION SOURCES.
NEVER SMOKE WHILE SERVICING THE VEHICLE.
Remove the fuel tank to service the fuel pump. Re-
fer to Fuel Tank Section for fuel tank removal. (1) Using a hammer and a brass drift punch care-
fully tap lock ring counter clockwise to release pump
(Fig. 11).
Fig. 10 Fuel Pressure Gauge and Adapter
14 - 8 FUEL SYSTEMS Ä