Pressure fuel regulator OPEL FRONTERA 1998 Workshop Manual

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–4
ENGINE DRIVEABILITY AND EMISSIONS
Knock Sensor 6E–337. . . . . . . . . . . . . . . . . . . . . . . . .
Linear Exhaust Gas Recirculation (EGR)
Control 6E–337. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Mass Air Flow (MAF) Sensor 6E–337. . . . . . . . . . . .
Manifold Absolute Pressure (MAP) Sensor 6E–338
Powertrain Control Module (PCM) 6E–338. . . . . . .
PCM Function 6E–338. . . . . . . . . . . . . . . . . . . . . . . . .
PCM Components 6E–339. . . . . . . . . . . . . . . . . . . . .
PCM Voltage Description 6E–339. . . . . . . . . . . . . . .
PCM Input/Outputs 6E–339. . . . . . . . . . . . . . . . . . . .
PCM Service Precautions 6E–339. . . . . . . . . . . . . .
Reprogramming The PCM 6E–339. . . . . . . . . . . . . .
Throttle Position (TP) Sensor 6E–339. . . . . . . . . . .
Transmission Fluid Temperature (TFT)
Sensor 6E–340. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Transmission Range Switch 6E–340. . . . . . . . . . . . .
Vehicle Speed Sensor (VSS) 6E–340. . . . . . . . . . . .
Use of Circuit Testing Tools 6E–340. . . . . . . . . . . . .
Aftermarket Electrical and Vacuum
Equipment 6E–340. . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrostatic Discharge Damage 6E–341. . . . . . . . .
Upshift Lamp 6E–341. . . . . . . . . . . . . . . . . . . . . . . . .
General Description (Air Induction) 6E–341. . . . . . . .
Air Induction System 6E–341. . . . . . . . . . . . . . . . . . .
General Description (Fuel Metering) 6E–341. . . . . . .
Acceleration Mode 6E–341. . . . . . . . . . . . . . . . . . . . .
Accelerator Controls 6E–341. . . . . . . . . . . . . . . . . . .
Battery Voltage Correction Mode 6E–341. . . . . . . .
CMP Signal 6E–341. . . . . . . . . . . . . . . . . . . . . . . . . . .
Clear Flood Mode 6E–342. . . . . . . . . . . . . . . . . . . . .
Deceleration Mode 6E–342. . . . . . . . . . . . . . . . . . . .
Engine Speed/Vehicle Speed/Fuel
Disable Mode 6E–342. . . . . . . . . . . . . . . . . . . . . . . .
Fuel Cutoff Mode 6E–342. . . . . . . . . . . . . . . . . . . . . .
Fuel Injector 6E–342. . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel Metering System Components 6E–342. . . . . . Fuel Metering System Purpose 6E–342. . . . . . . . . .
Fuel Pressure Regulator 6E–343. . . . . . . . . . . . . . . .
Fuel Pump Electrical Circuit 6E–343. . . . . . . . . . . . .
Fuel Rail 6E–343. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Idle Air Control (IAC) Valve 6E–343. . . . . . . . . . . . .
Run Mode 6E–344. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Starting Mode 6E–344. . . . . . . . . . . . . . . . . . . . . . . . .
Throttle Body Unit 6E–344. . . . . . . . . . . . . . . . . . . . .
General Description (Electronic Ignition
System) 6E–344. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Camshaft Position (CMP) Sensor 6E–344. . . . . . . .
Crankshaft Position (CKP) Sensor 6E–345. . . . . . .
Electronic Ignition 6E–345. . . . . . . . . . . . . . . . . . . . .
Ignition Coils 6E–345. . . . . . . . . . . . . . . . . . . . . . . . . .
Ignition Control 6E–345. . . . . . . . . . . . . . . . . . . . . . . .
Ignition Control PCM Output 6E–347. . . . . . . . . . . .
Knock Sensor (KS) PCM Input 6E–347
. . . . . . . . . .
Powertrain Control Module (PCM) 6E–347. . . . . . .
Spark Plug 6E–347. . . . . . . . . . . . . . . . . . . . . . . . . . . .
A/C Clutch Diagnosis 6E–349. . . . . . . . . . . . . . . . . . . .
A/C Clutch Circuit Operation 6E–349. . . . . . . . . . . .
A/C Clutch Circuit Purpose 6E–349. . . . . . . . . . . . .
A/C Request Signal 6E–349. . . . . . . . . . . . . . . . . . . .
General Description (Exhaust Gas
Recirculation (EGR) System) 6E–349. . . . . . . . . . . . .
EGR Purpose 6E–349. . . . . . . . . . . . . . . . . . . . . . . . .
Linear EGR Valve 6E–349. . . . . . . . . . . . . . . . . . . . .
Linear EGR Control 6E–349. . . . . . . . . . . . . . . . . . . .
Linear EGR Valve Operation and Results
of Incorrect Operation 6E–349. . . . . . . . . . . . . . . . .
EGR Pintle Position Sensor 6E–350. . . . . . . . . . . . .
General Description (Positive Crankcase
Ventilation (PCV) System) 6E–350. . . . . . . . . . . . . . .
Crankcase Ventilation System Purpose 6E–350. . .
Crankcase Ventilation System Operation 6E–350.

6E–5 ENGINE DRIVEABILITY AND EMISSIONS
Specifications
Tightening Specifications
ApplicationNꞏmLb Ft.Lb In.
Camshaft Position Sensor Retaining Screw9—78
Crankshaft Position Sensor Mounting Bolt10—87
EGR Bolt2821—
EGR Nut2821—
Engine Coolant Temperature Sensor207.7—
Fuel Drain Plug2922—
Fuel Pressure Regulator Attaching Screw6.5—60
Fuel Rail Bolts2518—
Fuel Tank Undercover Retaining Bolts3627—
Heated Oxygen Sensor4231—
Lower Intake Manifold to Engine Block Bolts2518—
Lower Intake Manifold to Engine Block Nuts2518—
Spark Plugs1813—
Throttle Body Mounting Bolts2518—
Upper Intake Manifold to Lower Intake Manifold Bolts2518—
VSS Retaining Bolt13—120
Vehicle Type Specifications
ECAUSTRALIA
THAILAND
SOUTH-EA
ST-ASIA
LATIN
AMERICAGULF
CONTRIES
SAUDI
CHINASOU
TH
AFRI
CA
EXPORTSpecifications
UBSUBSUBSUBSUBSUBS
OBD
O2
SENCATEGRMTATMTATMTATMTATMTMTATOBDSEN
SORAEGR
I21
I21
11
11
11
11
1
1
I

6E–29 ENGINE DRIVEABILITY AND EMISSIONS
Engine Component Locator Table
Number
NameLocation
1Linear Exhaust Gas Recirculation (EGR) ValveRear right side of the engine
2Throttle Position (TP) SensorOn the rear of the throttle body
3Intake Air Temperature (IAT) SensorOn the intake air duct near the throttle body
4Check Engine (MIL) LightOn the instrument panel beneath the
tachometer
5Positive Crankcase Ventilation (PCV) ValveOn the left of the cylinder head cover
6Air CleanerLeft front of the engine bay
7Mass Air Flow (MAF) SensorAttached to the air filter box
8Camshaft Position (CMP) SensorOn the rear right side at the left of the cylinder
head cover
9Fuel Pressure RegulatorRear right side of the engine
10Idle Air Control (IAC) ValveOn the left of the throttle body
11Upper Intake ManifoldTop of the engine
12Fuse/Relay BoxAlong the inside of the right fender
13Manifold Absolute Pressure (MAP) SensorBolted to the top of the upper intake manifold
14Throttle BodyBetween the intake air duct and the upper
intake manifold
15Engine Coolant Temperature SensorOn the coolant crossover pipe at the front of
the engine, near the throttle body

6E–31 ENGINE DRIVEABILITY AND EMISSIONS
Engine Component Locator Table
Number
NameLocation
1Linear Exhaust Gas Recirculation (EGR) ValveRear right side of the engine
2Throttle Position (TP) SensorOn the rear of the throttle body
3Intake Air Temperature (IAT) SensorOn the intake air duct near the throttle body
4Check Engine (MIL) LightOn the instrument panel beneath the
tachometer
5Positive Crankcase Ventilation (PCV) ValveOn the left of the cylinder head cover
6Air CleanerLeft front of the engine bay
7Mass Air Flow (MAF) SensorAttached to the air filter box
8Camshaft Position (CMP) SensorOn the rear right side at the left of the cylinder
head cover
9Fuel Pressure RegulatorRear right side of the engine
10Idle Air Control (IAC) ValveOn the left of the throttle body
11Upper Intake ManifoldTop of the engine
12Fuse/Relay BoxAlong the inside of the right fender
13Manifold Absolute Pressure (MAP) SensorBolted to the top of the upper intake manifold
14Throttle BodyBetween the intake air duct and the upper
intake manifold
15Engine Coolant Temperature SensorOn the coolant crossover pipe at the front of
the engine, near the throttle body

6E–60
ENGINE DRIVEABILITY AND EMISSIONS
Electronic Ignition System Diagnosis
If the engine cranks but will not run or immediately stalls,
the Engine Cranks But Will Not Start chart must be used
to determine if the failure is the ignition system or the fuel
system. If DTC P0341, or P0336 is set, the appropriate
diagnostic trouble code chart must be used for diagnosis.
If a misfire is being experienced with no DTC set, refer to
the
Symptoms section for diagnosis.
Fuel Metering System Check
Some failures of the fuel metering system will result in an
“Engine Cranks But Will Not Run” symptom. If this
condition exists, refer to the
Cranks But Will Not Run
chart. This chart will determine if the problem is caused
by the ignition system, the PCM, or the fuel pump
electrical circuit.
Refer to
Fuel System Electrical Test for the fuel system
wiring schematic.
If there is a fuel delivery problem, refer to
Fuel System
Diagnosis
, which diagnoses the fuel injectors, the fuel
pressure regulator, and the fuel pump. If a malfunction
occurs in the fuel metering system, it usually results in
either a rich HO2S signal or a lean HO2S signal. This
condition is indicated by the HO2S voltage, which causes
the PCM to change the fuel calculation (fuel injector pulse
width) based on the HO2S reading. Changes made to the
fuel calculation will be indicated by a change in the long
term fuel trim values which can be monitored with a Tech
2. Ideal long term fuel trim values are around 0%; for a
lean HO2S signal, the PCM will add fuel, resulting in a fuel
trim value above 0%. Some variations in fuel trim values
are normal because all engines are not exactly the same.
If the fuel trim values are greater than +23%, refer to
DTC
P0131, DTC P0151, DTC P0171, and DTC 1171
f o r i t e m s
which can cause a lean HO2S signal.
Idle Air Control (IAC) Valve
The Tech 2 displays the IAC pintle position in counts. A
count of “0” indicates the PCM is commanding the IAC
pintle to be driven all the way into a fully-seated position.
This is usually caused by a large vacuum leak.
The higher the number of counts, the more air is being
commanded to bypass the throttle blade. Refer to IAC
System Check in order to diagnose the IAC system.
Refer to
Rough, Unstable, or Incorrect Idle, Stalling in
Symptoms for other possible causes of idle problems.
Fuel System Pressure Test
A fuel system pressure test is part of several of the
diagnostic charts and symptom checks. To perform this
test, refer to
Fuel Systems Diagnosis.
Fuel Injector Coil Test Procedure and
Fuel Injector Balance Test Procedure
T32003
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart:
2. Relieve the fuel pressure by connecting the
5-8840-0378-0 Fuel Pressure Gauge to the fuel
pressure connection on the fuel rail.
CAUTION: In order to reduce the risk of fire and
personal injury, wrap a shop towel around the fuel
pressure connection. The towel will absorb any fuel
leakage that occurs during the connection of the fuel
pressure gauge. Place the towel in an approved
container when the connection of the fuel pressure
gauge is complete.
Place the fuel pressure gauge bleed hose in an
approved gasoline container.
With the ignition switch “OFF,” open the valve on the
fuel pressure gauge.
3. Record the lowest voltage displayed by the DVM
after the first second of the test. (During the first
second, voltage displayed by the DVM may be
inaccurate due to the initial current surge.)
Injector Specifications:
Resistance Ohms
Voltage Specification at
10
C-35C (50F-95F)
11.8 – 12.65.7 – 6.6
The voltage displayed by the DVM should be within
the specified range.
The voltage displayed by the DVM may increase
throughout the test as the fuel injector windings
warm and the resistance of the fuel injector windings
changes.

6E–85 ENGINE DRIVEABILITY AND EMISSIONS
Fuel System Electrical Test
D06RW101
Circuit Description
When the ignition switch is first turned “ON,” the
powertrain control module (PCM) energizes the fuel
pump relay which applies power to the in-tank fuel pump.
The fuel pump relay will remain “ON” as long as the
engine is running or cranking and the PCM is receiving
58X crankshaft position pulses. If no 58X crankshaft
position pulses are present, the PCM de-energizes the
fuel pump relay within 2 seconds after the ignition is
turned “ON” or the engine is stopped.
The fuel pump delivers fuel to the fuel rail and injectors,
then to the fuel pressure regulator. The fuel pressure
regulator controls fuel pressure by allowing excess fuel to
be returned to the fuel tank. With the engine stopped and
ignition “ON,” the fuel pump can be turned “ON” by using a
command by Tech 2.
Diagnostic Aids
An intermittent 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.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
2. If the fuel pump is operating but incorrect pressure is
noted, the fuel pump wiring is OK and the “Fuel
System Pressure Test” chart should be used for
diagnosis.

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.

6E–90
ENGINE DRIVEABILITY AND EMISSIONS
Fuel System Diagnosis
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. Turn the ignition “OFF.”
2. Turn the air conditioning system “OFF.”
3. Relieve fuel system pressure and install the fuel
pressure gauge.
4. Turn the ignition “ON.”
NOTE: The fuel pump will run for approximately 2
seconds. Use Tech 2 to command the fuel pump “ON”.
5. Observe the fuel pressure indicated by the fuel
pressure gauge with the fuel pump running.
Is the fuel pressure within the specified limits?
290-376 kPa
(42-55 psi)
Go to Step 3Go to Step 17
3NOTE: The fuel pressure will drop when the fuel pump
stops running, then it should stabilize and remain
constant.
Does the fuel pressure indicated by the fuel pressure
gauge remain constant?
—Go to Step 4Go to Step 12
41. When the vehicle is at normal operation
temperature, turn the ignition “ON” to build fuel
pressure and observe the measurement on the
gauge.
2. Start the engine and observe the fuel pressure
gauge.
Did the reading drop by the amount specified after the
engine was started?
21-105 kPa
(3-15 psi)
Go to Step 5Go to Step 9
5Is fuel pressure dropping off during acceleration,
cruise, or hard cornering?
—Go to Step 6
Check for
improper fuel
6Visually and physically inspect the following items for a
restriction:
The in-pipe fuel filter.
The fuel feed line.
Was a restriction found?
—Verify repairGo to Step 7
7Remove the fuel tank and visually and physically
inspect the following items:
The fuel pump strainer for a restriction.
The fuel line for a leak.
Verify that the correct fuel pump is in the vehicle.
Was a problem found in any of these areas?
—Verify repairGo to Step 8
8Replace the fuel pump.
Is the action complete?
—Verify repair—
91. Disconnect the vacuum hose from the fuel pressure
regulator.
2. With the engine idling, apply 12-14 inches of
vacuum to the fuel pressure regulator.
Does the fuel pressure indicated by the fuel pressure
gauge drop by the amount specified?
21-105 kPa
(3-15 psi)
Go to Step 10Go to Step 11