1998 ISUZU TROOPER fuel pressure

6A±13
ENGINE MECHANICAL
Condition CorrectionPossible cause
Engine knockingPreignition due to use of spark plugs
of inadequate heat rangeInstall Spark Plugs of adequate heat
range
Carbon deposits in combustion
chambersClean
Fuel too low in octane ratingReplace fuel
Wide Open Throttle enrichment
system failureRefer to Section 6E
Selection of transmission gear
incorrectCaution operator of incorrect gear
selection
Engine overheatingRefer to ªEngine Lacks Powerº
OthersWater pump defectiveReplace
Drive belt slippingReplace auto tentioner or drive belt
Abnormal Combustion
ConditionPossible causeCorrection
Trouble in fuel systemFuel pressure control valve defectiveReplace
Fuel filter cloggedReplace
Fuel pump cloggedClean or replace
Fuel tank or fuel pipe cloggedClean or replace
Fuel injector cloggedClean or replace
Fuel pump relay defectiveReplace
Power supply cable for fuel pump
broken or poor connectionsReconnect, correct or replace
Mass Airflow (MAF) sensor circuit
open or defectiveCorrect or replace
MAF Sensor defectiveReplace
Manifold Absolute Pressure Sensor
circuit open or shortedCorrect or replace
Manifold Absolute Pressure Sensor
defectiveReplace
Engine Coolant Temperature (ECT)
Sensor circuit open or shortedCorrect or replace
ECT Sensor defectiveReplace
Throttle Position Sensor adjustment
incorrectReadjust
Throttle Position Sensor defectiveReplace
Throttle Position Sensor connector
poor connectionsReconnect
Vehicle Speed Sensor cable poor
connections or defectiveCorrect or replace
Vehicle Speed Sensor loosely fixedFix tightly
Vehicle Speed Sensor in wrong
contact or defectiveReplace
Powertrain Control Module cable
poor connections or defectiveCorrect or replace

6A±17
ENGINE MECHANICAL
Malfunction Indicator Lamp
The instrument panel ªCHECK ENGINEº Malfunction
Indicator Lamp (MIL) illuminates by self diagnosticsystem when the system checks the starting of engine, or
senses malfunctions.
Condition
Possible causeCorrection
ªCHECK ENGINEº MIL does not
illuminate at the starting of engine
Bulb defectiveReplace
illuminate at the starting of engineMIL circuit openCorrect or replace
Command signal circuit to operate
self diagnostic system shortedCorrect or replace
Engine Control Module (PCM) cable
loosely connected, disconnected or
defectiveCorrect or replace
PCM defectiveReplace
ªCHECK ENGINEº MIL illuminates,
and stays onDeterioration of heated oxygen
sensor internal elementReplace
Heated oxygen sensor connector
terminal improper contactReconnect properly
Heated oxygen sensor lead wire
shortedCorrect
Heated oxygen sensor circuit openCorrect or replace
Deterioration of engine coolant
temperature sensor internal elementReplace
Engine coolant temperature sensor
connector terminal improper contactReconnect properly
Engine coolant temperature sensor
lead wire shortedCorrect
Engine coolant temperature sensor
circuit openCorrect or replace
Throttle position sensor open or
shorted circuitsCorrect or replace
Deterioration of crankshaft position
sensorReplace
Crankshaft position sensor circuit
open or shortedCorrect or replace
Vehicle speed sensor circuit openCorrect or replace
Manifold absolute pressure sensor
circuit open or shortedCorrect or replace
Intake air temperature sensor circuit
open or shortedCorrect or replace
Fuel injector circuit open or shortedCorrect or replace
PCM driver transistor defectiveReplace PCM
Malfunctioning of PCM RAM
(Random Access Memory) or ROM
(Read Only Memory)Replace PCM

6A±18
ENGINE MECHANICAL
Cylinder Head Cover LH
Removal
1. Disconnect battery ground cable.
2. Drain engine coolant from faucet bottom of radiator.
3. Remove engine cover from the dowels on the
common chamber.
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4. Remove air cleaner duct assembly (3) and air cleaner
element (4).
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Legend
(1) Positive Crankcase Ventilation Hose Connector
(2) Intake Air Temperature Sensor
(3) Air Cleaner Duct Assembly
(4) Air Cleaner Element
(5) Mass Air Flow Sensor
NOTE: Disconnect the mass air flow (MAF) sensor
connector, intake air temperature (IAT) sensor connector,
and positive crankcase ventilation (PCV) hose before
hand the air cleaner duct assembly is removed.5. Disconnect following wiring connectors and bonding
cable:

Manifold Absolute Pressure (MAP) sensor

Vacuum Switching Valve (VSV) for Induction Air
Control Valve (IACV) actuator

Ignition coils for left bank

Fuel injectors for left bank

Idle air control (IAC) valve

Throttle position sensor (TPS)

Bonding cable

Others as necessitated
6. Disconnect following vacuum hoses:

Brake master VAC

Canister

VSV for IACV actuator

Duty solenoid valve

PCV
7. Disconnect radiator upper and lower hoses
8. Remove engine harness from the cylinder head
cover.
9. Remove the upper fan guide.
10. Remove cooling fan and clutch assembly.
11. Remove drive belt by pushing down the auto
tensioner using spanner as illustrated.
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6A±24
ENGINE MECHANICAL
Common Chamber
Removal
1. Disconnect battery ground cable.
2. Remove air cleaner duct assembly.
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Legend
(1) Positive Crankcase Ventilation Hose Connector
(2) Intake Air Temperature Sensor
(3) Air Cleaner Duct Assembly
(4) Air Cleaner Element
(5) Air Flow Sensor
3. Disconnect accelerator pedal cable from throttle body
and cable bracket.
4. Disconnect vacuum booster hose from common
chamber.
5. Disconnect connector from manifold absolute
pressure sensor, idle air control valve, throttle
position sensor, solenoid valve, electric vacuum
sensing valve, and EGR valve.
6. Disconnect vacuum hose on canister VSV and
positive crankcase ventilation hose, fuel rail
assembly with pressure control valve bracket.
7. Remove ventilation hose from throttle valve and
intake duct and remove water hose.
8. Remove the four throttle body fixing bolts.
9. Remove exhaust gas recirculation valve assembly
fixing bolt and nut on common chamber and remove
EGR valve assembly.
10. Remove two bolts from common chamber rear side
for remove fuel hose bracket.
11. Remove common chamber four bolts and four nuts
then remove the common chamber.
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Legend
(1) Common Chamber
(2) Throttle Valve Assembly
(3) Bolt
Installation
1. Install common chamber and tighten bolts and nuts to
the specified torque.
Torque :
Bolt : 25 N´m (2.5 Kg´m/18 lb ft)
Nut : 25 N´m (2.5 Kg´m/18 lb ft)
2. Install fuel hose bracket and tighten bolts to specified
torque.
Torque : 10 N´m (1.0 Kg´m/89 lb in)
3. Install exhaust gas recirculation valve assembly and
tighten bolt and nut to the specified torque.
Torque : 25 N´m (2.5 Kg´m/18 lb ft)
4. Install throttle body and tighten bolts to the specified
torque.
Torque : 25 N´m (2.5 Kg´m/18 lb ft)
5. Install ventilating hose to throttle valve and intake
duct.
6. Connect vacuum hoses on canister VSV and positive
crankcase ventilation hose. Tighten bolts for fuel rail
assembly with pressure control valve bracket.
Torque : 25 N´m (2.5 Kg´m/18 lb ft)
7. Connect each connector without fail.
8. Connect vacuum booster hose.
9. Connect accelerator pedal cable.
Accelerator pedal cable adjustment
1. Loosen the adjusting nut and screw cap.
2. Pull outer cable while fully closing the throttle
valve.

6C±2
ENGINE FUEL
General Description
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Legend
(1) Fuel Filler Cap
(2) Fuel Tank
(3) Rollover Valve
(4) Fuel Pump
(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
When working on the fuel system, there are several
things to keep in mind:

Any time the fuel system is being worked on,
disconnect the negative battery cable except for
those tests where battery voltage is required.

Always keep a dry chemical (Class B) fire
extinguisher near the work area.
Replace all pipes with the same pipe and fittings that
were removed.

Clean and inspect ªOº rings. Replace if required.

Always relieve the line pressure before servicing any
fuel system components.

Do not attempt repairs on the fuel system until you
have read the instructions and checked the pictures
relating to that repair.

6C±3
ENGINE FUEL

Adhere to all Notices and Cautions.
All gasoline engines are designed to use only unleaded
gasoline. Unleaded gasoline must be used for proper
emission control system operation.
Its use will also minimize spark plug fouling and extend
engine oil life. Using leaded gasoline can damage the
emission control system and could result in loss of
emission warranty coverage.
All cars are equipped with an Evaporative Emission
Control System. The purpose of the system is to minimize
the escape of fuel vapors to the atmosphere.
Fuel Metering
The Engine Control Module (ECM) is in complete control
of this fuel delivery system during normal driving
conditions.
The intake manifold function, like that of a diesel, is used
only to let air into the engine. The fuel is injected by
separate injectors that are mounted over the intake
manifold.
The Manifold Absolute Pressure (MAP) sensor measures
the changes in the intake manifold pressure which result
from engine load and speed changes, which the MAP
sensor converts to a voltage output.
This sensor generates the voltage to change
corresponding to the flow of the air drawn into the engine.
The changing voltage is transformed into an electric
signal and provided to the ECM.
With receipt of the signals sent from the MAP sensor,
Intake Air Temperature sensor and others, the ECM
determines an appropriate fuel injection pulse width
feeding such information to the fuel injector valves to
effect an appropriate air/fuel ratio.
The Multiport Fuel Injection system utilizes an injection
system where the injectors turn on at every crankshaft
revolution. The ECM controls the injector on time so that
the correct amount of fuel is metered depending on
driving conditions.
Two interchangeable ªOº rings are used on the injector
that must be replaced when the injectors are removed.
The fuel rail is attached to the top of the intake manifold
and supplies fuel to all the injectors.
Fuel is recirculated through the rail continually while the
engine is running. This removes air and vapors from the
fuel as well as keeping the fuel cool during hot weather
operation.
The fuel pressure control valve that is mounted on the fuel
rail maintains a pressure differential across the injectors
under all operating conditions. It is accomplished by
controlling the amount of fuel that is recirculated back to
the fuel tank based on engine demand.
See Section ªDriveability and Emissionº for more
information and diagnosis.

6C±5
ENGINE FUEL
Installation
1. Install the fuel filter in the proper direction.
2. Install fuel filter holder fixing bolt.
3. Connect fuel hoses on engine side(1) and fuel tank
side(2).
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4. Install fuel filler cap
5. Connect the battery ground cable.
Inspection
After installation, start engine and check for fuel leakage.
In±Tank Fuel Filter
The filter is located on the lower end of fuel pickup tube in
the fuel tank. It prevents dirt from entering the fuel pipe
and also stops water unless the filter is completely
submerged in the water. It is a self cleaning type, not
requiring scheduled maintenance. Excess water and
sediment in the tank restricts fuel supply to the engine,
resulting in engine stoppage. In such a case, the tank
must be cleaned thoroughly.
Fuel Pump Flow Test
If reduction of fuel supply is suspected, perform the
following checks:
1. Make sure that there is fuel in the tank.
2. With the engine running, check the fuel feed pipe and
hose from fuel tank to injector for evidence of
leakage. Retighten, if pipe or hose connection is
loose. Also, check pipes and hoses for squashing or
clogging.
3. Insert the hose from fuel feed pipe into a clean
container, and check for fuel pump flow rate.4. Connect the pump relay terminals with a jumper
wire(1) as shown and start the fuel pump to measure
delivery.
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CAUTION: Never generate sparks when connecting
a jumper wire.
Delivery
Delivery
15 seconds0.38 liters minimum
If the measure value is out of standard, conduct the
pressure test.
Pressure test
For the pressure test to the fuel system, see Section 6E
ªFuel Control Systemº.

6C±8
ENGINE FUEL
7. Disconnect two fuel tank wiring connectors(4) on
front right side of tank.
8. Disconnect evapo fuel hose(5).
9. Disconnect fuel feed tube and fuel return tube(6).
NOTE: Handling of the fuel tube, be sure to refer ªFuel
Tube/Quick±Connect Fittingsº in this section.
10. Remove fuel tank fixing bolts on both sides and
remove fuel tank(7).
Installation
1. Install fuel tank(7).

Place a flange on right side of tank on the bracket.
Install a flange on left side on the bracket from the
bottom, and tighten bolts to the specified torque.
Torque: 36 N´m (3.7 Kg´m/27 lb ft)
2. Connect fuel feed tube and fuel return tube(6).
3. Connect evapo fuel hose(5).
4. Connect fuel tank wiring connector(4).
5. Install undercover(3).
6. Connect fuel filler hose, air breather hose and evapo
hose(2).
7. Install fender liner(1).

Mount fender liner to the wheel well.

Fill the tank with fuel and tighten fuel filler cap.

Connect battery ground cable.
Fuel Tube / Quick ± Connect Fittings
Precautions

Lighting of Fires Prohibited.

Keep flames away from your work area to prevent the
inflammable from catching fire.

Disconnect the battery negative cable to prevent
shorting during work.

When welding or conducting other heat-generating
work on other parts, be sure to provide pretreatment
to protect the piping system from thermal damage or
spattering.
Cautions During Work
Do not expose the assembly to battery electrolyte or do
not wipe the assembly with a cloth used to wipe off spilt
battery electorolyte.
The piping wet with battery electrolyte cannot be used.
Be careful not to give a bending or twisting force to the
piping during the work. If deformed, replace with a new
piping.
Removal
1. Open the fuel cap to relieve the fuel pressure in the
tank.
If the fuel quick-connect fittings are dusty, clean with
an air blower, etc. and then remove it.
141RW016As some pressure may remain in the piping, cover the
connector with a cloth, etc. to prevent the splashing
of fuel in the first disconnection of the piping.