fuel cap OPEL FRONTERA 1998 User Guide

6C–11
ENGINE FUEL
Fuel Gauge Unit
Fuel Gauge Unit and Associated Parts
140RS004
Legend
(1) Wiring Connector
(2) Fuel Gauge Unit
Removal
CAUTION: When repair to the fuel system has been
completed, start engine and check the fuel system
for loose connection or leakage. For the fuel system
diagnosis, see Section “Driveability and Emission”.
1. Disconnect battery ground cable.
2. Loosen fuel filler cap.
3. Drain fuel.
Tighten drain plug to the specified torque after
draining fuel.
Torque: 20 Nꞏm (2.0 Kgꞏm/14 lb ft) — M8
4. Wiring connector
Disconnect wiring connector(1) from the unit.
5. Fuel gauge unit
Remove the fixing screws, then the fuel gauge
unit(2).
NOTE: After removing fuel gauge unit, cover fuel tank to
prevent any dust entering
Installation
1. Fuel gauge unit(2).
2. Wiring connector(1).
Connect the wiring connector to the fuel gauge unit.
Fill the tank with fuel and tighten fuel filler cap.
Connect battery ground cable.

6C–12
ENGINE FUEL
Fuel Filler Cap
General Description
Fuel filler cap includes vacuum valve and pressure valve.
In case any high vacuum and any high pressure happen in
tank, each valve works to adjust the pressure to prevent
the tank from being damaged.
140RW021
Legend
(1) Vacuum Valve
(2) Pressure Valve
Inspection
Check the seal ring in the filler cap for presence of any
abnormality and for seal condition.
Replace the filler cap, if abnormal.
CAUTION: The fuel filler cap valves have
characteristics.
A defective valve, no valve at all or a valve with the
wrong characteristics will do a lot of harm to engine
operating characteristics; be sure to use the same
fuel filler cap as installed in this vehicle.
Main Data and Specifications
Torque Specification
Nꞏm (Kgꞏm/lb ft)
035RW141

6E–3 ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0351
Ignition 1 Control Circuit 6E–206. . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0352
Ignition 2 Control Circuit 6E–209. . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0353
Ignition 3 Control Circuit 6E–212. . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0354
Ignition 4 Control Circuit 6E–215. . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0355
Ignition 5 Control Circuit 6E–218. . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0356
Ignition 6 Control Circuit 6E–221. . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0402
EGR Pintle Crank Error 6E–224. . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0404
EGR Open Stuck 6E–226. . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0405
EGR Low Voltage 6E–228. . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0406
EGR High Voltage 6E–231. . . . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0502
VSS Circuit Low Input 6E–234. . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0562
System Voltage Low 6E–237. . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0563
System Voltage High 6E–239. . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P0601
PCM Memory 6E–240. . . . . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P1154
HO2S Circuit Transition Time Ratio Bank 2
Sensor 1 6E–241. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P1171
Fuel System Lean During Acceleration 6E–245. . . .
Diagnostic Trouble Code (DTC) P1380
ABS Rough Road ABS System Fault 6E–248. . . . . .
Diagnostic Trouble Code (DTC) P1404
EGR Closed Stuck 6E–249. . . . . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P1508
IAC System Low RPM 6E–251. . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P1509
IAC System High RPM 6E–254. . . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P1618
Serial Peripheral Interface (SPI) PCM
Interprocessor Communication Error 6E–257. . . . . .
Diagnostic Trouble Code (DTC) P1625
PCM Unexpected Reset 6E–258. . . . . . . . . . . . . . . . .
Diagnostic Trouble Code (DTC) P1640
Driver-1-Input High Voltage 6E–259. . . . . . . . . . . . . .
Symptom Diagnosis 6E–262. . . . . . . . . . . . . . . . . . . . .
Default Matrix Table 6E–288. . . . . . . . . . . . . . . . . . . . .
Camshaft Position (CMP) Sensor 6E–291. . . . . . . . . .
Crankshaft Position (CKP) Sensor 6E–292. . . . . . . . .
Engine Coolant Temperature (ECT) Sensor 6E–292.
Heated Oxygen Sensor (HO2S) 6E–293. . . . . . . . . . .
Intake Air Temperature (IAT) Sensor 6E–295. . . . . . .
Knock Sensor (KS) 6E–296. . . . . . . . . . . . . . . . . . . . . . Mass Air Flow (MAF) Sensor 6E–297. . . . . . . . . . . . .
Manifold Absolute Pressure (MAP) Sensor 6E–297.
Malfunction Indicator Lamp (MIL) 6E–298. . . . . . . . . .
Powertrain Control Module (PCM) 6E–298. . . . . . . . .
EEPROM 6E–300. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Steering Pressure (PSP) Switch 6E–300
. . . .
Throttle Position (TP) Sensor 6E–301. . . . . . . . . . . . .
Vehicle Speed Sensor (VSS) 6E–302. . . . . . . . . . . . .
Air Cleaner/Air Filter 6E–303. . . . . . . . . . . . . . . . . . . . .
Idle Air Control (IAC) Valve 6E–304. . . . . . . . . . . . . . .
Common Chamber 6E–305. . . . . . . . . . . . . . . . . . . . . .
Accelerator Cable Assembly 6E–305. . . . . . . . . . . . . .
Accelerator Pedal Replacement 6E–308. . . . . . . . . . .
Fuel Filter Cap 6E–310. . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel Filter 6E–310. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel Gauge Unit 6E–313. . . . . . . . . . . . . . . . . . . . . . . .
Fuel Injectors 6E–314. . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel Pressure Regulator 6E–315. . . . . . . . . . . . . . . . .
Fuel Metering System 6E–317. . . . . . . . . . . . . . . . . . . .
Fuel Pump Assembly 6E–318. . . . . . . . . . . . . . . . . . . .
Fuel Pump Relay 6E–319. . . . . . . . . . . . . . . . . . . . . . . .
Fuel Rail Assembly 6E–319. . . . . . . . . . . . . . . . . . . . . .
Fuel Tank 6E–321. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Throttle Body (TB) 6E–323. . . . . . . . . . . . . . . . . . . . . . .
Electronic Ignition System 6E–324. . . . . . . . . . . . . . . .
Catalytic Converter 6E–325. . . . . . . . . . . . . . . . . . . . . .
Air Conditioning Relay 6E–325. . . . . . . . . . . . . . . . . . .
EVAP Canister Hoses 6E–326. . . . . . . . . . . . . . . . . . . .
EVAP Canister 6E–326. . . . . . . . . . . . . . . . . . . . . . . . . .
EVAP Canister Purge Solenoid 6E–327. . . . . . . . . . . .
Fuel Tank Vent Valve 6E–328. . . . . . . . . . . . . . . . . . . .
Linear Exhaust Gas Recirculation
(EGR) Valve 6E–328. . . . . . . . . . . . . . . . . . . . . . . . . . .
Positive Crankcase Ventilation (PCV) Valve 6E–329.
Wiring and Connectors 6E–330. . . . . . . . . . . . . . . . . . .
PCM Connectors and Terminals 6E–330. . . . . . . . . . .
Wire Harness Repair: Twisted Shielded
Cable 6E–330. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Twisted Leads 6E–331. . . . . . . . . . . . . . . . . . . . . . . . . .
Weather-Pack Connector 6E–332. . . . . . . . . . . . . . . . .
Com-Pack III 6E–333. . . . . . . . . . . . . . . . . . . . . . . . . . .
Metri-Pack 6E–333. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General Description 6E–335. . . . . . . . . . . . . . . . . . . . .
General Description (PCM and Sensors) 6E–335. . .
58X Reference PCM Input 6E–335. . . . . . . . . . . . . .
A/C Request Signal 6E–335. . . . . . . . . . . . . . . . . . . .
Crankshaft Position (CKP) Sensor 6E–335. . . . . . .
Camshaft Position (CMP) Sensor and
Signal 6E–335. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Coolant Temperature (ECT) Sensor 6E–335
Electrically Erasable Programmable Read
Only Memory (EEPROM) 6E–336. . . . . . . . . . . . . .
Fuel Control Heated Oxygen Sensors 6E–336. . . .
Intake Air Temperature (IAT) Sensor 6E–336. . . . .

6E–38
ENGINE DRIVEABILITY AND EMISSIONS
General Service Information
OBD Serviceablity Issues
The list of non-vehicle faults that could affect the
performance of the OBD system has been compiled.
These non-vehicle faults vary from environmental
conditions to the quality of fuel used.
The illumination of the MIL (“Check Engine” lamp) due to
a non-vehicle fault could lead to misdiagnosis of the
vehicle, increased warranty expense and customer
dissatisfaction. The following list of non-vehicle faults
does not include every possible fault and may not apply
equally to all product lines.
Fuel Quality
Using fuel with the wrong octane rating for your vehicle
may cause driveability problems. Many of the major fuel
companies advertise that using “premium” gasoline will
improve the performance of your vehicle. Most premium
fuels use alcohol to increase the octane rating of the fuel.
Although alcohol-enhanced fuels may raise the octane
rating, the fuel’s ability to turn into vapor in cold
temperatures deteriorates. This may affect the starting
ability and cold driveability of the engine.
Low fuel levels can lead to fuel starvation, lean engine
operation, and eventually engine misfire.
Non-OEM Parts
All of the OBD diagnostics have been calibrated to run
with OEM parts. Something as simple as a
high-performance exhaust system that affects exhaust
system back pressure could potentially interfere with the
operation of the EGR valve and thereby turn on the MIL
(“Check Engine” lamp). Small leaks in the exhaust
system near the post catalyst oxygen sensor can also
cause the MIL (“Check Engine” lamp) to turn on.
Aftermarket electronics, such as cellular phones,
stereos, and anti-theft devices, may radiate EMI into the
control system if they are improperly installed. This may
cause a false sensor reading and turn on the MIL (“Check
Engine” lamp).
Environment
Temporary environmental conditions, such as localized
flooding, will have an effect on the vehicle ignition system.
If the ignition system is rain-soaked, it can temporarily
cause engine misfire and turn on the MIL (“Check Engine”
lamp).
Poor Vehicle Maintenance
The sensitivity of OBD diagnostics will cause the MIL
(“Check Engine” lamp) to turn on if the vehicle is not
maintained properly. Restricted air filters, fuel filters, and
crankcase deposits due to lack of oil changes or improper
oil viscosity can trigger actual vehicle faults that were not
previously monitored prior to OBD. Poor vehicle
maintenance can not be classified as a “non-vehicle
fault”, but with the sensitivity of OBD diagnostics, vehicle
maintenance schedules must be more closely followed.Related System Faults
Many of the OBD system diagnostics will not run if the
PCM detects a fault on a related system or component.
One example would be that if the PCM detected a Misfire
fault, the diagnostics on the catalytic converter would be
suspended until Misfire fault was repaired. If the Misfire
fault was severe enough, the catalytic converter could be
damaged due to overheating and would never set a
Catalyst DTC until the Misfire fault was repaired and the
Catalyst diagnostic was allowed to run to completion. If
this happens, the customer may have to make two trips to
the dealership in order to repair the vehicle.
Maintenance Schedule
Refer to the Maintenance Schedule.
Visual / Physical Engine Compartment
Inspection
Perform a careful visual and physical engine
compartment inspection when performing any diagnostic
procedure or diagnosing the cause of an emission test
failure. This can often lead to repairing a problem without
further steps. Use the following guidelines when
performing a visual/physical inspection:
Inspect all vacuum hoses for punches, cuts,
disconnects, and correct routing.
Inspect hoses that are difficult to see behind other
components.
Inspect all wires in the engine compartment for proper
connections, burned or chafed spots, pinched wires,
contact with sharp edges or contact with hot exhaust
manifolds or pipes.
Basic Knowledge of Tools Required
NOTE: Lack of basic knowledge of this powertrain when
performing diagnostic procedures could result in an
incorrect diagnosis or damage to powertrain
components. Do not attempt to diagnose a powertrain
problem without this basic knowledge.
A basic understanding of hand tools is necessary to effec-
tively use this section of the Service Manual.
Serial Data Communications
Class II Serial Data Communications
This vehicle utilizes the “Class II” communication system.
Each bit of information can have one of two lengths: long
or short. This allows vehicle wiring to be reduced by
transmitting and receiving multiple signals over a single
wire. The messages carried on Class II data streams are
also prioritized. If two messages attempt to establish
communications on the data line at the same time, only
the message with higher priority will continue. The device
with the lower priority message must wait. The most
significant result of this regulation is that it provides Tech 2
manufacturers with the capability to access data from any
make or model vehicle that is sold.

6E–40
ENGINE DRIVEABILITY AND EMISSIONS
Common OBD Terms
Diagnostic
When used as a noun, the word diagnostic refers to any
on-board test run by the vehicle’s Diagnostic
Management System. A diagnostic is simply a test run on
a system or component to determine if the system or
component is operating according to specification. There
are many diagnostics, shown in the following list:
Oxygen sensors
Oxygen sensor heaters
EGR
Catalyst monitoring
Enable Criteria
The term “enable criteria” is engineering language for the
conditions necessary for a given diagnostic test to run.
Each diagnostic has a specific list of conditions which
must be met before the diagnostic will run. “Enable
criteria” is another way of saying “conditions required”.
The enable criteria for each diagnostic is listed on the first
page of the DTC description under the heading
“Conditions for Setting the DTC”. Enable criteria varies
with each diagnostic, and typically includes, but is not
limited to the following items:
engine speed
vehicle speed
ECT
MAF/MAP
barometric pressure
IAT
TP
fuel trim
TCC enabled
A/C on
Tr i p
Technically, a trip is a key on-run-key off cycle in which all
the enable criteria for a given diagnostic are met, allowing
the diagnostic to run. Unfortunately, this concept is not
quite that simple. A trip is official when all the enable
criteria for a given diagnostic are met. But because the
enable criteria vary from one diagnostic to another, the
definition of trip varies as well. Some diagnostic are run
when the vehicle is at operating temperature, some when
the vehicle first start up; some require that the vehicle be
cruising at a steady highway speed, some run only when
the vehicle is idle; some diagnostics function with the
TCC disables. Some run only immediately following a
cold engine start-up.
A trip then, is defined as a key on-run-key off cycle in
which the vehicle was operated in such a way as to satisfy
the enables criteria for a given diagnostic, and this
diagnostic will consider this cycle to be one trip. However,
another diagnostic with a different set of enable criteria
(which were not met) during this driving event, would not
consider it a trip. No trip will occur for that particular
diagnostic until the vehicle is driven in such a way as to
meet all the enable criteria.
The Diagnostic Executive
The Diagnostic Executive is a unique segment of
software which is designed to coordinate and prioritize
the diagnostic procedures as well as define the protocol
for recording and displaying their results. The main
responsibilities of the Diagnostic Executive are listed as
following:
Commanding the MIL (“Check Engine” lamp) on and
off
DTC logging and clearing
Freeze Frame data for the first emission related DTC
recorded
Non-emission related Service Lamp (future)
Operating conditions Failure Records buffer, (the
number of records will vary)
Current status information on each diagnostic
The Diagnostic Executive records DTCs and turns on the
MIL when emission-related faults occur. It can also turn
off the MIL if the conditions cease which caused the DTC
to set.
Diagnostic Information
The diagnostic charts and functional checks are designed
to locate a faulty circuit or component through a process
of logical decisions. The charts are prepared with the
requirement that the vehicle functioned correctly at the
time of assembly and that there are not multiple faults
present.
There is a continuous self-diagnosis on certain control
functions. This diagnostic capability is complemented by
the diagnostic procedures contained in this manual. The
language of communicating the source of the malfunction
is a system of diagnostic trouble codes. When a
malfunction is detected by the control module, a
diagnostic trouble code is set and the Malfunction
Indicator Lamp (MIL) (“Check Engine” lamp) is
illuminated.
Malfunction Indicator Lamp (MIL)
The Malfunction Indicator Lamp (MIL) looks the same as
the MIL you are already familiar with (“Check Engine”
lamp). However, OBD requires that the it illuminate under
a strict set of guide lines.
Basically, the MIL is turned on when the PCM detects a
DTC that will impact the vehicle emissions.
The MIL is under the control of the Diagnostic Executive.
The MIL will be turned on if an emissions-related
diagnostic test indicates a malfunction has occurred. It
will stay on until the system or component passes the
same test, for three consecutive trips, with no
emissionsrelated faults.
Extinguishing the MIL
When the MIL is on, the Diagnostic Executive will turn off
the MIL after
three consecutive trips that a “test passed”
has been reported for the diagnostic test that originally
caused the MIL to illuminate.
Although the MIL has been turned off, the DTC will remain
in the PCM memory (both Freeze Frame and Failure
Records) until
forty(40) warm-up cycles after no faults
have been completed.

6E–41 ENGINE DRIVEABILITY AND EMISSIONS
If the MIL was set by either a fuel trim or misfire-related
DTC, additional requirements must be met. In addition to
the requirements stated in the previous paragraph, these
requirements are as follows:
The diagnostic tests that are passed must occur with
375 RPM of the RPM data stored at the time the last
test failed.
Plus or minus ten (10) percent of the engine load that
was stored at the time the last failed.
Similar engine temperature conditions (warmed up or
warming up ) as those stored at the time the last test
failed.
Meeting these requirements ensures that the fault which
turned on the MIL has been corrected.
The MIL (“Check Engine” lamp) is on the instrument
panel and has the following function:
It informs the driver that a fault affects vehicle emission
levels has occurred and that the vehicle should be
taken for service as soon as possible.
As a bulb and system check, the MIL will come “ON”
with the key “ON” and the engine not running. When
the engine is started, the MIL will turn “OFF.”
When the MIL remains “ON” while the engine is
running, or when a malfunction is suspected due to a
driveability or emissions problem, a Powertrain
On-Board Diagnostic (OBD ll) System Check must be
performed. The procedures for these checks are given
in On-Board Diagnostic (OBD) System Check. These
checks will expose faults which may not be detected if
other diagnostics are performed first.
DTC Types
Each DTC is directly related to a diagnostic test. The
Diagnostic Management System sets DTC based on the
failure of the tests during a trip or trips. Certain tests must
fail two (2) consecutive trips before the DTC is set. The
following are the four (4) types of DTCs and the
characteristics of those codes:
Ty p e A
Emissions related
Requests illumination of the MIL of the first trip with a
fail
Stores a History DTC on the first trip with a fail
Stores a Freeze Frame (if empty)
Stores a Fail Record
Updates the Fail Record each time the diagnostic
test fails
Ty p e B
Emissions related
“Armed” after one (1) trip with a fail
“Disarmed” after one (1) trip with a pass
Requests illumination of the MIL on the second
consecutive trip
with a fail
Stores a History DTC on the second consecutive trip
with a fail (The DTC will be armed after the first fail)
Stores a Freeze Frame on the second consecutive
trip with a fail (if empty)
Stores a Fail Record when the first test fails (not
dependent on
consecutive trip fails)
Updates the Fail Record each time the diagnostic
test fails
Type C (if the vehicle is so equipped)
Non-Emissions related
Requests illumination of the Service Lamp or the
service message on the Drive Information Center
(DIC) on the
first trip with a fail
Stores a History DTC on the first trip with a fail
Does not store a Freeze Frame
Stores Fail Record when test fails
Updates the Fail Record each time the diagnostic
test fails
Type D (Ty p e D non-emissions related are not utilized
on certain vehicle applications).
Non-Emissions related
Dose not request illumination of any lamp
Stores a History DTC on the first trip with a fail
Does not store a Freeze Frame
Stores Fail Record when test fails
Updates the Fail Record each time the diagnostic
test fails
IMPORTANT:Only four Fail Records can be stored.
Each Fail Record is for a different DTC. It is possible that
there will not be Fail Records for every DTC if multiple
DTCs are set.
Storing and Erasing Freeze Frame Data and Failure
Records
The data captured is called Freeze Frame data. The
Freeze Frame data is very similar to a single record of
operating conditions. Whenever the MIL is illuminated,
the corresponding record of operating conditions is
recorded to the Freeze Frame buffer.
Data from these faults take precedence over data
associated with any other fault. The Freeze Frame data
will not be erased unless the associated history DTC is
cleared.
Each time a diagnostic test reports a failure, the current
engine operating conditions are recorded in the
Failure
Records
buffer. A subsequent failure will update the
recorded operating conditions. The following operating
conditions for the diagnostic test which failed
typically
include the following parameters:
Air Fuel Ratio
Air Flow Rate
Fuel Trim
Engine Speed
Engine Load
Engine Coolant Temperature
Vehicle Speed
TP Angle
MAP/BARO
Injector Base Pulse Width
Loop Status

6E–80
ENGINE DRIVEABILITY AND EMISSIONS
Circuit Description
The electronic Ignition system uses a coil-at-plug method
of spark distribution. In this type of ignition system, the
powertrain control module (PCM) triggers the correct
driver inside the ignition coil, which then triggers the
correct ignition coil based on the 58X signal received from
the crankshaft position sensor (CKP). The spark plug
connected to the coil fires when the ICM opens the ground
circuit for the coil’s primary circuit.
During crank, the PCM monitors the CKP 58X signal. The
CKP signal is used to determine which cylinder will fire
first. After the CKP 58X signal has been processed by the
PCM, it will command all six injectors to allow a priming
shot of fuel for all the cylinders. After the priming, the
injectors are left “OFF” during the next six 58X reference
pulses from the CKP. This allows each cylinder a chance
to use the fuel from the priming shot. During this waiting
period, a camshaft position (CMP) signal pulse will have
been received by the PCM. The CMP signal allows the
PCM to operate the injectors sequentially based on
camshaft position. If the camshaft position signal is not
present at start-up, the PCM will begin sequential fuel
delivery with a 1-in-6 chance that fuel delivery is correct.
The engine will run without a CMP signal, but will set a
DTC code.
Diagnostic Aids
An intermittent problem may be caused by a poor
connection, rubbed-through wire insulation or a wire
broken inside the insulation. Check for the following
items:
Poor connection or damaged harness – Inspect the
PCM harness and connectors for improper mating,
broken locks, improperly formed or damaged
terminals, poor terminal-to-wire connection, and
damaged harness.
Faulty engine coolant temperature sensor – Using
Tech 2, compare engine coolant temperature with
intake air temperature on a completely cool engine.
Engine coolant temperature should be within 10
C of
intake air temperature. If not, replace the ECT sensor.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
5. An obvious cause of low fuel pressure would be an
empty fuel tank.
6. The engine will easily start and run if a few injectors
are disabled. It is not necessary to test all injectors
at this time since this step is only a test to verify that
all of the injectors have not been disabled by fuel
contamination.
7. A blinking test light verifies that the PCM is
monitoring the 58X crankshaft reference signal and
is capable of activating the injectors. If there is an
open or shorted driver circuit, DTCs 201-206 should
be set.
19.By using a spark tester, each ignition coil’s ability to
produce 25,000 volts is verified.
25.If there is an open or shorted driver circuit, DTCs
201-206 should be set. All six injector driver circuits
can be checked at one time without removing the
intake manifold if a 5-8840-2636-0 test light is
available. This is the alternative procedure:
With the ignition “OFF,” disconnect the gray
connector located at the rear of the air filter, attached
to a bracket on the purge canister.
Connect test light 5-8840-2636-0 to the connector.
Do any of the light constantly illuminate or fail to blink
when the engine is cranked? If so, repair the short or
open circuit, or replace the PCM if indicated.
This procedure only tests the driver circuit as far as the
test connection, so step 31 is added to test the circuit all
the way to the injector.

6E–86
ENGINE DRIVEABILITY AND EMISSIONS
CAUTION: To reduce the risk of fire and personal
injury:
It is necessary to relieve fuel system pressure
before connecting a fuel pressure gauge. Refer to
Fuel Pressure Relief Procedure, below.
A small amount of fuel may be released when
disconnecting the fuel lines. Cover fuel line
fittings with a shop towel before disconnecting, to
catch any fuel that may leak out. Place the towel in
an approved container when the disconnect is
completed.
Fuel Pressure Relief Procedure
1. Remove the fuel cap.
2. Remove the fuel pump relay from the underhood
relay center.
3. Start the engine and allow it to stall.
4. Crank the engine for an additional 3 seconds.
Fuel Gauge Installation
1. Remove the shoulder fitting cap.
2. Install fuel gauge 5-8840-0378-0 to the fuel feed line
located in front of and above the right side valve train
cover .
3. Reinstall the fuel pump relay.
Fuel System Electrical Test
StepActionVa l u e ( s )Ye sNo
1Was the “On-Board Diagnostic (OBD) System Check”
performed?
—Go to Step 2
Go to OBD
System
Check
21. Read the “Caution” above.
2. Relieve the fuel system pressure and install the fuel
pump pressure gauge to the test fitting.
3. Use Tech 2 to command the fuel pump “ON.”
Is there an immediate pressure build-up which
indicates the pump is running?
—Go to Step 3Go to Step 4
31. Verify that the pump is not running by removing the
fuel filler cap and listening.
2. Command the pump “ON” with Tech 2.
Did the pump turn “OFF” after 2 seconds?
—
Te s t
completed
Go to Step 12
41. Ignition “OFF.”
2. Remove the fuel pump relay.
3. Using a test light connected to ground, probe the
battery feed to the relay.
Did the light illuminate?
—Go to Step 6Go to Step 5
5Repair short or open battery feed to fuel pump relay.
Is the action complete?
—Verify repair—
61. Connect a test light between the two wires that
connect to the fuel pump relay pull-in coil.
2. Ignition “ON.”
Did the test light illuminate for 2 seconds and then turn
off?
—Go to Step 12Go to Step 7
71. With a test light connected to battery (–), probe the
fuel pump relay connector at the wire which runs
from the relay pull-in coil to the PCM.
2. Ignition “ON.”
Did the test light illuminate for 2 seconds and then turn
off?
—Go to Step 8Go to Step 9
8Locate and repair open in the fuel pump relay ground
circuit.
Is the action complete?
—Verify repair—

6E–88
ENGINE DRIVEABILITY AND EMISSIONS
Fuel System Diagnosis
140RW020
Legend
(1) Fuel Filler Cap
(2) Fuel Tank
(3) Rollover Valve
(4) Fuel Pump and Sender Assembly
(5) Fuel Filter
(6) Fuel Rail Right
(7) Right Bank(8) Fuel Rail Left
(9) Left Bank
(10) Fuel Pressure Control Valve
(11) Common Chamber
(12) Duty Solenoid Valve
(13) Throttle Valve
(14) Canister
(15) Evapo Shut Off Valve
Circuit Description
When the ignition switch is turned “ON,” the powertrain
control module (PCM) will turn “ON” the in-tank fuel
pump. The in-tank fuel pump will remain “ON” as long as
the engine is cranking or running and the PCM is receiving
58X crankshaft position pulses. If there are no 58X
crankshaft position pulses, the PCM will turn the in-tank
fuel pump “OFF” 2 seconds after the ignition switch is
turned “ON” or 2 seconds after the engine stops running.
The in-tank fuel pump is an electric pump within an
integral reservoir. The in-tank fuel pump supplies fuel
through an in-line fuel filter to the fuel rail assembly. The
fuel pump is designed to provide fuel at a pressure above
the pressure needed by the fuel injectors. A fuel pressure
regulator, attached to the fuel rail, keeps the fuel available
to the fuel injectors at a regulated pressure. Unused fuel
is returned to the fuel tank by a separate fuel return line.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
2. Connect the fuel pressure gauge to the fuel feed line
as shown in the fuel system illustration. Wrap a
shop towel around the fuel pressure connection in
order to absorb any fuel leakage that may occur
when installing the fuel pressure gauge. With the
ignition switch “ON” and the fuel pump running, the
fuel pressure indicated by the fuel pressure gauge
should be 333-376 kPa (48-55 psi). This pressure
is controlled by the amount of pressure the spring
inside the fuel pressure regulator can provide.
3. A fuel system that cannot maintain a constant fuel
pressure has a leak in one or more of the following
areas:
The fuel pump check valve.
The fuel pump flex line.

6E–89 ENGINE DRIVEABILITY AND EMISSIONS
The valve or valve seat within the fuel pressure
regulator.
The fuel injector(s).
4. Fuel pressure that drops off during acceleration,
cruise, or hard cornering may case a lean condition.
A lean condition can cause a loss of power, surging,
or misfire. A lean condition can be diagnosed using
a Tech II Tech 2. If an extremely lean condition
occurs, the oxygen sensor(s) will stop toggling. The
oxygen sensor output voltage(s) will drop below 500
mV. Also, the fuel injector pulse width will increase.
IMPORTANT:Make sure the fuel system is not
operating in the “Fuel Cut-Off Mode.”
When the engine is at idle, the manifold pressure is
low (high vacuum). This low pressure (high vacuum)
is applied to the fuel pressure regulator diaphragm.
The low pressure (high vacuum) will offset the
pressure being applied to the fuel pressure regulator
diaphragm by the spring inside the fuel pressure
regulator. When this happens, the result is lower fuel
pressure. The fuel pressure at idle will vary slightly as
the barometric pressure changes, but the fuel
pressure at idle should always be less than the fuel
pressure noted in step 2 with the engine “OFF.”
16.Check the spark plug associated with a particular
fuel injector for fouling or saturation in order to
determine if that particular fuel injector is leaking. If
checking the spark plug associated with a particular
fuel injector for fouling or saturation does not
determine that a particular fuel injector is leaking,
use the following procedure:
Remove the fuel rail, but leave the fuel lines and
injectors connected to the fuel rail. Refer to
Fuel Rail
Assembly
in On-Vehicle Service.
Lift the fuel rail just enough to leave the fuel injector
nozzles in the fuel injector ports.
CAUTION: In order to reduce the risk of fire and
personal injury that may result from fuel spraying on
the engine, verify that the fuel rail is positioned over
the fuel injector ports and verify that the fuel injector
retaining clips are intact.
Pressurize the fuel system by connecting a 10 amp
fused jumper between B+ and the fuel pump relay
connector.
Visually and physically inspect the fuel injector
nozzles for leaks.
17.A rich condition may result from the fuel pressure
being above 376 kPa (55 psi). A rich condition may
cause a DTC P0132 or a DTC P0172 to set.
Driveability conditions associated with rich
conditions can include hard starting (followed by
black smoke) and a strong sulfur smell in the
exhaust.20.This test determines if the high fuel pressure is due
to a restricted fuel return line or if the high fuel
pressure is due to a faulty fuel pressure regulator.
21.A lean condition may result from fuel pressure
below 333 kPa (48 psi). A lean condition may
cause a DTC P0131 or a DTC P0171 to set.
Driveability conditions associated with lean
conditions can include hard starting (when the
engine is cold ), hesitation, poor driveability, lack of
power, surging , and misfiring.
22.Restricting the fuel return line causes the fuel
pressure to rise above the regulated fuel pressure.
Command the fuel pump “ON” with Tech 2. The fuel
pressure should rise above 376 kPa (55 psi) as the
fuel return line becomes partially closed.
NOTE: Do not allow the fuel pressure to exceed 414 kPa
( 6 0 p s i ) . F u e l p r e s s u r e i n e x c e s s o f 4 1 4 k P a ( 6 0 p s i ) m a y
damage the fuel pressure regulator.
CAUTION: To reduce the risk of fire and personal
injury:
It is necessary to relieve fuel system pressure
before connecting a fuel pressure gauge. Refer to
Fuel Pressure Relief Procedure, below.
A small amount of fuel may be released when
disconnecting the fuel lines. Cover fuel line
fittings with a shop towel before disconnecting, to
catch any fuel that may leak out. Place the towel in
an approved container when the disconnect is
completed.
Fuel Pressure Relief Procedure
1. Remove the fuel cap.
2. Remove the fuel pump relay from the underhood
relay center.
3. Start the engine and allow it to stall.
4. Crank the engine for an additional 3 seconds.
Fuel Gauge Installation
1. Remove the shoulder fitting cap.
2. Install fuel gauge 5-8840-0378-0 to the fuel feed line
located in front of and above the right side valve train
cover.
3. Reinstall the fuel pump relay.