2007 ISUZU KB P190 open gas tank

6C-2 FUEL SYSTEM (4JK1/4JJ1)
Fuel System
Service Precautions
Parts of the fuel system such as the internal part of the
fuel injector, and holes and clearances that form
passages for fuel are finished to a very high degree o
f
accuracy. They are therefore highly sensitive to foreign
matter and the entry of foreign matter could cause
damage to the fuel passage. Therefore, effective
measures should be taken to prevent the entry o
f
foreign matter.
If a water removal agent is used in the fuel then it will
absorb moisture in the light oil and may cause rust.
Therefore, do not use a water removal agent in the fuel
tank.
W hen servicing the fuel system, every precaution must
be taken to prevent the entry of foreign material into the
system.
• Before beginning the service procedure, wash the
fuel line and the surrounding area.
• Perform the service procedures with clean hands.
Do not wear work gloves.
• Immediately after removing the fuel hose and/o
r
fuel pipe, carefully tape vinyl bags over the
exposed ends of the hose or pipe.
• If parts are to be replaced (fuel hose, fuel pipe,
etc.) do not open the new part packaging until
installation.
Discard gaskets and O-rings and replace them with ne
w
ones.

Work procedure
•
The fuel opening must be quickly sealed when
removing the fuel pipe, injection pipe, fuel injector,
fuel supply pump, and fuel rail.
• The eyebolts and gasket must be stored in a clean
parts box with a lid to prevent adhesion of foreign
matter.
• Fuel leakage could cause fires. Therefore, afte
r
finishing the work, wipe off the fuel that has leaked
out and make sure there is no fuel leakage afte
r
starting the engine.

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ENGINE DIAGNOSIS (C24SE) 6-3
3.Trouble in Fuel System Condition Possible cause Correction
Starting motor turns over and
spark occurs but engine does not
start. Fuel tank empty Fill

Water in fuel system Clean
Fuel filter clogged Replace filter
Fuel pipe clogged Clean or replace
Fuel pump defective Replace
Fuel pump circuit open Correct or replace
Evaporative Emission Control
system circuit clogged Correct or replace

Multiport Fuel Injection System
faulty Refer to "Electronic Fuel Injection"
section
4.Engine Lacks Compression
Condition Possible cause Correction
Engine lacks compression Spark plug loosely fitted or spark
plug gasket defective Tighten to specified torque or
replace gasket
Spark plug wire incorrect Connect properly or replace
Valve timing incorrect Adjust
Cylinder head gasket defective Replace gasket
Valve incorrectly seated Lap valve
Valve stem seized Replace valve and valve guide
Valve spring weakened Replace
Cylinder or piston rings worn Overhaul engine
Piston ring seized Overhaul engine.

Engine Compression Test Procedure
1. Start and run the engine until the engine
reaches normal operating temperature.
2. Turn the engine off.
3. Remove all the spark plugs.
4. Remove ignition coil fuse (15A) and disable the ignition system.
5. Remove the fuel pump relay from the relay and fuse box. 6. Engage the starter and check that the cranking
speed is approximately 300 rpm.
7. Install cylinder compression gauge into spark plug hole.
8. With the throttle valve opened fully, keep the starter engaged until the compression gauge
needle reaches the maximum level. Note the
reading.
9. Repeat the test with each cylinder. The pressure difference between the individual
cylinders should not exceed 100kPa (14.5 psi).


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6E–52 ENGINE DRIVEABILITY AND EMISSIONS
GENERAL DESCRIPTION FOR FUEL
METERING
The fuel metering system starts with the fuel in the fuel
tank. An electric fuel pump, located in the fuel tank,
pumps fuel to the fuel rail through an in-line fuel filter.
The pump is designed to provide fuel at a pressure
above the pressure needed by the injectors.
A fuel pressure regulator in the fuel rail keeps fuel
available to the fuel injectors at a constant pressure.
A return line delivers unused fuel back to the fuel tank.
The basic function of the air/fuel metering system is to
control the air/fuel delivery to the engine. Fuel is
delivered to the engine by individual fuel injectors
mounted in the intake manifold.
The main control sensor is the heated oxygen sensor
located in the exhaust system. The heated oxygen
sensor reports to the ECM how much oxygen is in the
exhaust gas. The ECM changes the air/fuel ratio to the
engine by controlling the amount of time that fuel
injector is “On”.
The best mixture to minimize exhaust emissions is 14.7
parts of air to 1 part of gasoline by weight, which allows
the catalytic converter to operate most efficiently.
Because of the constant measuring and adjusting of the
air/fuel ratio, the fuel injection system is called a “closed
loop” system.
The ECM monitors signals from several sensors in
order to determine the fuel needs of the engine. Fuel is
delivered under one of several conditions called “mode”.
All modes are controlled by the ECM.
Battery Voltage Correction Mode
When battery voltage is low, the ECM will compensate
for the weak spark by increasing the following:
• The amount of fuel delivered.
• The idle RPM.
Clear Flood Mode
Clear a flooded engine by pushing the accelerator pedal
down all the way. The ECM then de-energizes the fuel
injectors. The ECM holds the fuel injectors de-energized
as long as the throttle remains above 75% and the
engine speed is below 800 RPM. If the throttle position
becomes less than 75%, the ECM again begins to pulse
the injectors ON and OFF, allowing fuel into the
cylinders.
Deceleration Fuel Cutoff (DFCO) Mode
The ECM reduces the amount of fuel injected when it
detects a decrease in the throttle position and the air
flow. When deceleration is very fast, the ECM may cut
off fuel completely. Until enable conditions meet the
engine revolution less 1000 rpm or manifold absolute
pressure less than 10 kPa.
Engine Speed/ Vehicle Speed/ Fuel Disable
Mode
The ECM monitors engine speed. It turns off the fuel
injectors when the engine speed increases above 6000
RPM. The fuel injectors are turned back on when
engine speed decreases below 3500 RPM.
Acceleration Mode
The ECM provides extra fuel when it detects a rapid
increase in the throttle position and the air flow.
Fuel Cutoff Mode
No fuel is delivered by the fuel injectors when the
ignition is OFF. This prevents engine run-on. In addition,
the ECM suspends fuel delivery if no reference pulses
are detected (engine not running) to prevent engine
flooding.
Starting Mode
When the ignition is first turned ON, the ECM energizes
the fuel pump relay for two seconds to allow the fuel
pump to build up pressure. The ECM then checks the
engine coolant temperature (ECT) sensor and the
throttle position sensor to determine the proper air/fuel
ratio for starting.
The ECM controls the amount of fuel delivered in the
starting mode by adjusting how long the fuel injectors
are energized by pulsing the injectors for very short
times.
Run Mode
The run mode has the following two conditions:
• Open loop
• Closed loop
When the engine is first started, the system is in “open
loop” operation. In “Open Loop,” the ECM ignores the
signal from the heated oxygen sensor (HO2S). It
calculates the air/fuel ratio based on inputs from the TP,
ECT, and MAP sensors.
The system remains in “Open Loop” until the following
conditions are met:
• The HO2S has a varying voltage output showing that it is hot enough to operate properly (this depends on
temperature).
• The ECT has reached a specified temperature.
• A specific amount of time has elapsed since starting the engine.
• Engine speed has been greater than a specified RPM since start-up.
The specific values for the above conditions vary with
different engines and are stored in the programmable
read only memory (PROM). When these conditions are
met, the system enters “closed loop” operation. In
“closed loop,” the ECM calculates the air/fuel ratio
(injector on-time) based on the signal from the HO2S.
This allows the air/fuel ratio to stay very close to 14.7:1.

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ENGINE DRIVEABILITY AND EMISSIONS 6E–57
GENERAL DESCRIPTION FOR
EVAPORATIVE EMISSION SYSTEM
EVAP Emission Control System Purpose
The basic evaporative emission control system used on
the charcoal canister storage method. The method
transfers fuel vapor from the fuel tank to an activated
carbon (charcoal) storage devise to hold the vapors
when the vehicle is not operating.
The canister is located on the rear axle housing by the
frame cross-member.
When the engine is running, the fuel vapor is purged
from the carbon element by intake air flow and
consumed in the normal combustion process.
EVAP Emission Control System Operation
The EVAP canister purge is controlled by a solenoid
valve that allows the manifold vacuum to purge the
canister. The engine control module (ECM) supplies a
ground to energize the solenoid valve (purge on). The
EVAP purge solenoid control is pulse-width modulated
(PWM) (turned on and off several times a second). The
duty cycle (pulse width) is determined by engine
operating conditions including load, throttle position,
coolant temperature and ambient temperature. The duty
cycle is calculated by the ECM. the output is
commanded when the appropriate conditions have
been met. These conditions are:
• The engine is fully warmed up.
• The engine has been running for a specified time.
• The IAT reading is above 10°C (50°F).
• Purge/Vacuum Hoses. Made of rubber compounds, these hoses route the gasoline fumes from their
sources to the canister and from the canister to the
intake air flow.
• EVAP Canister. Mounted on a bracket ahead of the fuel tank, the canister stores fuel vapors until the
ECM determined that engine conditions are right for
them to be removed and burned.
Poor idle, stalling and Poor driveability can be caused
by:
• A malfunctioning purge solenoid.
• A damaged canister.
• Hoses that are split, cracked, or not connected properly.
System Fault Detection
The EVAP leak detection strategy is based on applying
vacuum to the EVAP system and monitoring vacuum
decay. At an appropriate time, the EVAP purge solenoid
is turned “ON,” allowing the engine vacuum to draw a
small vacuum on the entire evaporative emission
system.
After the desired vacuum level has been achieved, the
EVAP purge solenoid is turned “OFF,” sealing the
system. A leak is detected by monitoring for a decrease
in vacuum level over a given time period, all other
variables remaining constant.
If the desired vacuum level cannot be achieved in the
test described above, a large leak or a faulty EVAP
purge control solenoid valve is indicated.
Leaks can be caused by the following conditions:
• Missing or faulty fuel cap
• Disconnected, damaged, pinched, or blocked EVAP purge line
• Disconnected, damaged, pinched, or blocked fuel tank vapor line
• Disconnected or faulty EVAP purge control solenoid valve
• Open ignition feed circuit to the purge solenoid
(1) Purge Solenoid Valve
(2) From Canistor to Purge Solenoid
(3) From Purge Solenoid to Intake
(1) Canistor
(2) Air Separator
132
12

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ENGINE DRIVEABILITY AND EMISSIONS 6E–111
10 Locate and repair the loss of vacuum to the fuelpressure regulator.
Is the action complete? — Verify repair —
11 Replace the fuel pressure regulator. Is the action complete? — Verify repair —
12 1. Run the fuel pump with the Scan Tool. 2. After pressure has built up, turn off the pump andclamp the supply hose shut with suitable locking
pliers.
Does the fuel pressure indicated by the fuel pressure
gauge remain constant? — Go to Step 13Go to Step 15
13 Visually inspect the fuel supply line and repair any leaks.
Was a problem found? — Verify repair Go to Step 14
14 Remove the fuel tank and inspect for leaky hose or in- tank fuel line.
Was a problem found? — Verify repair Go to Step 8
15 1. If the pliers are still clamped to the fuel supply hose, remove the locking pliers.
2. With suitable locking pliers, clamp the fuel return line to prevent fuel from returning to the fuel tank.
3. Run the fuel pump with the Scan Tool.
4. After pressure has built up, remove power to the pump.
Does the fuel pressure indicated by the fuel pressure
gauge remain constant? — Go to Step 11Go to Step 16
16 Locate and replace any leaking fuel injector(s). Is the action complete? — Verify repair —
17 Is the fuel pressure indicated by the fuel pressure gauge above the specified limit? 376 kPa
(55 psi) Go to Step 18Go to Step 21
18 1. Relieve the fuel pressure. Refer to the Fuel
Pressure Relief .
2. Disconnect the fuel return line from the fuel rail.
3. Attach a length of flexible hose to the fuel rail return outlet passage.
4. Place the open end of the flexible hose into an approved gasoline container.
5. Run the fuel pump with the Scan Tool.
6. 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 19Go to Step 20
19 Locate and correct the restriction in the fuel return line.
Is the action complete? — Verify repair —
20 Visually and physically inspect the fuel rail outlet passages for a restriction.
Was a restriction found? — Verify repair Go to Step 11
21 Is the fuel pressure indicated by the fuel pressure gauge above the specified value? 0 kPa (0 psi) Go to Step 22Go to Step 23
Step
Action Value(s) Yes No

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6E–254 ENGINE DRIVEABILITY AND EMISSIONS
DETONATION/SPARK KNOCK SYMPTOM
DEFINITIONS: A mild to severe ping, usually worse under acceleration. The engine makes a sharp metallic knocking
sound that changes with throttle opening. Prolonged detonation may lead to complete engine tailure.
Step Action Value(s) Yes No
1 Was the “ On-Board Diagnostic (OBD) System Check ”
performed? — Go to Step 2Go to
OBD
System Check
2 1. Perform a bulletin search. 2. If a bulletin that addresses the symptom is found,correct the condition as instructed in the bulletin.
Was a bulletin found that addresses the symptom? — Verify repair Go to Step 3
3 Was a visual/physical check performed? —Go to Step 4Go to
Visual /
physical Check .
4 1. If Tech 2 readings are normal (refer to Typical Scan Data Values) and there are no engine
mechanical faults, fill the fuel tank with a known
quality gasoline.
2. Re-evaluate the vehicle performance.
Is detonation present? — Go to Step 5Verify repair
5 1. Check for obvious overheating problems: • Low engine coolant
• Restricted air flow to radiator
• Incorrect coolant solution
2. If a problem is found, repair as necessary.
Was a problem found? — Verify repair Go to Step 6
6 Check the fuel pressure. Refer to 6E-108 page “ Fuel
System Diagnosis” .
Was a problem found? — Verify repair Go to Step 7
7 1. Using a Tech 2, display the MAP sensor value in comparison with atmosphere temperature.
2. Check for a faulty, plugged, or incorrectly installed MAP sensor.
Was the problem found? — Verify repair Go to Step 8
8 1. Using a Tech 2, display the ECT sensor and IAT sensor value and warm up condition compared
with the typical data.
2. Check the specified value or wire.
Was the problem found? — Verify repair Go to Step 9
9 Observe the throttle position display on the Tech 2 while slowly increasing throttle pedal.
Does the throttle position increase steady with
increasing smoothly?
—Go to Step 10Refer to
Diagnostic
Trouble Code P0123 for further
diagnosis
10 Check the knock sensor wire, shield wire, or installation condition.
Was a problem found? — Verify repair Go to Step 11
11 Check items that can cause the engine to run lean. Refer to DTC P1171 “Fuel Supply System Lean
During Power Enrichment”.
Was a problem found? — Verify repair Go to Step 12

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Engine Management – V6 – General Information Page 6C1-1–35

5 Abbreviations and Glossary of
Te r m s
Abbreviations and terms used in this Section are listed below in alphabetical order with an explanation of the
abbreviation or term.
Abbreviation Description
A/C Air-conditioning
AC Alternating Current – An electrical current where the polarity is constantly changing between positive and
negative
A/F Air / Fuel (A/F Ratio)
Analogue Signal An electrical signal that constantly varies in voltage within a given parameter
Barometric Pressure Barometric absolute pressure (atmospheric pressure)
CAN Controller Area Network – A type of serial data for communication between electronic devices.
Catalytic Converter
A muffler-shaped device fitted in the exhaust system, usually close to the engine. Through chemical reaction,
a catalytic converter converts harmful gases produced by the combustion process such as HC, CO, and NOx,
into environmentally safe water vapour, carbon dioxide, and nitrogen.
CKT Circuit
Closed Loop A fuel control mode of operation that uses the signal from the exhaust oxygen sensor(s), to control the air / fuel
ratio precisely at a 14.7 to 1 ratio. This allows maximum efficiency of the catalytic converter.
CO Carbon Monoxide. One of the gases produced by the engine combustion process.
DC Direct Current
Digital Signal An electrical signal that is either on or off.
DLC
Data Link Connector. Used at the assembly plant to evaluate the engine management system. For service, it
allows the use of Tech 2 in performing system checks.
DLC Data Stream An output from the ECM initiated by Tech 2 and transmitted via the Data Link Connector(DLC).
DMM (10 M Ω) Digital Multimeter. A multipurpose meter that has capability of measuring voltage, current flow and resistance.
A digital multimeter has an input impedance of 10 M Ω (megohms), which means they draw very little power
from the device under test, they are very accurate and will not damage delicate electronic components
Driver An electronic device, usually a power transistor, that operates as an electrical switch.
DTC
Diagnostic Trouble Code. If a fault occurs in the engine management system, the ECM may set a four digit
diagnostic trouble code (DTC) which represents the fault condition. Tech 2 is used to interface with the ECM
and access the DTC(s). The ECM may also operate the malfunction indicator lamp in the instrument cluster.
Duty Cycle The time, in percentage, that a circuit is on versus off.
ECT Sensor
Engine Coolant Temperature sensor. A device that provides a variable voltage to the ECM based on the
temperature of the engine coolant.
EEPROM Electrically Erasable Programmable Read Only Memory. A type of read only memory (ROM) that can be
electrically programmed, erased and reprogrammed using Tech 2. Also referred to as Flash Memory
EMI or Electrical
Noise An unwanted signal interfering with a required signal. A common example is the effect of high voltage power
lines on an AM radio.
Engine Braking A condition where the engine is used to slow the vehicle on closed throttle or low gear.
EPROM Erasable Programmable Read Only Memory. A type of Read Only Memory (ROM) that can be erased with
ultraviolet light and then reprogrammed.
ESD Electrostatic Discharge. The discharge of static electricity which has built up on an insulated material
EVAP
Evaporative emission control system. Used to prevent fuel vapours from the fuel tank from entering into the
atmosphere. The vapours are stored in a canister that contains an activated charcoal element. The fuel
vapours are purged from the canister into the manifold to be burned in the engine.
GM LAN General Motors Local Area Network - A type of serial data for communication between electronic devices.
Fuse
A thin metal strip which melts when excessive current flows through it, creating an open circuit and protecting
a circuit from damage.
HC Hydrocarbon. Result of unburned fuel produced by incomplete combustion.
Heavy Throttle Approximately 3/4 of accelerator pedal travel (75% throttle position)
IAT Sensor
Intake Air Temperature sensor. A device that provides a variable voltage to the ECM based on the
temperature of air entering the intake system.
Ideal Mixture The air / fuel ratio which provides the best performance, while maintaining maximum conversion of exhaust
emissions, typically 14.7 to 1 on spark ignition engines
IGN Ignition
Inputs Information from sensors (MAF, TP, etc.) and switches (A/C request, etc.) used by the ECM to determine how
to control its outputs.

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