2004 ISUZU TF SERIES fuel pressure

6E–386 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
24 Using the Tech 2 or the vacuum pump and check the
EGR valve operation for the following condition
through the small window.
ÅERestrict shaft movement. Check for objects sticking
the shaft, broken diaphragm or ex cessive carbon
deposit.
Tech 2:
1. Using the Tech 2, ignition "On" and engine "On".
2. Select the "Miscellaneous Test" and perform the
"EGR Solenoid Test" in the "Solenoid".
3. Operate the Tech 2 in accordance with procedure.
Solenoid 95%: EGR Valve Open
Solenoid 5%: EGR Valve Close
Vacuum Pump:
1. Using the vacuum pump. Disconnect the original
vacuum hose and connect the hose to the EGR
valve.
2. Apply vacuum pressure.
Vacuum Apply: EGR Valve Open
Vacuum Release: EGR Valve Close
If a problem is found, repair as necessary.
Was the problem found?—Verify repair Go to Step 25
25 Check the ex haust system for a possible restriction.
Damaged or collapsed pipes or catalytic converter.
Internal muffler failure.
If a problem is found, repair as necessary.
Was a problem found?—Verify repair Go to Step 26
26 Visually/physically inspect for the following conditions.
Restrict fuel supply system. Check for a pinched
fuel hose/pipe.
Check for a condition that causes fuel wax ing or
icing, such as the customer is using an incorrect
fuel type in winter season or water mix ed with the
fuel.
If a problem is found, repair as necessary.
Was a problem found?—Verify repair Go to Step 27
27 Replace the fuel filter.
Was the problem solved?—Verify repair Go to Step 28 Step Action Value(s) Yes No

Vacuum Pump Small Window

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–393
26 Using the Tech 2 or the vacuum pump and check the
EGR valve operation for the following condition
through the small window.
ÅERestrict shaft movement. Check for objects sticking
the shaft, broken diaphragm or ex cessive carbon
deposit.
Tech 2:
1. Using the Tech 2, ignition "On" and engine "On".
2. Select the "Miscellaneous Test" and perform the
"EGR Solenoid Test" in the "Solenoid".
3. Operate the Tech 2 in accordance with procedure.
Solenoid 95%: EGR Valve Open
Solenoid 5%: EGR Valve Close
Vacuum Pump:
1. Using the vacuum pump. Disconnect the original
vacuum hose and connect the hose to the EGR
valve.
2. Apply vacuum pressure.
Vacuum Apply: EGR Valve Open
Vacuum Release: EGR Valve Close
If a problem is found, repair as necessary.
Was the problem found?—Verify repair Go to Step 27
27 Visually/physically inspect for the following conditions.
Restrict fuel supply system. Check for a pinched
fuel hose/pipe.
Check for a condition that causes fuel wax ing or
icing, such as the customer is using an incorrect
fuel type in winter season or water mix ed with the
fuel.
If a problem is found, repair as necessary.
Was a problem found?—Verify repair Go to Step 28
28 Replace the fuel filter.
Was the problem solved?—Verify repair Go to Step 29 Step Action Value(s) Yes No

Vacuum Pump Small Window

6E–402 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
POOR FUEL ECONOMY SYMPTOM
DEFINITIONS: Fuel economy, as measured by an actual road test, is noticeably lower than expected. Also, economy
is noticeably lower than it was on this vehicle at one time, as previously shown by an actual road test. (Larger than
standard tires will cause odometer readings to be incorrect, and that may cause fuel economy to appear poor when it
is actually normal.)
Step Action Value(s) Yes No
1Was the “On-Board Diagnostic (OBD) System Check”
performed?
—Go to Step 2Go to On Board
Diagnostic
(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 visually/physical check performed?
—Go to Step 4Go to Visual /
physical Check
4 Check owner's driving habits.
Is the A/C “On” full time?
Are tires at the correct pressure?
Are ex cessively heavy loads being carried?
Is acceleration too much, too often?—Go to Step 5Go to Step 6
5 Review the items in Step 4 with the customer and
advise as necessary.
Is the action complete?—System OK—
6 Check for low engine coolant level.
Was a problem found? —Verify repair Go to Step 7
7 Check for incorrect or faulty engine thermostat. Refer
to Engine Cooling.
Was a problem found?—Verify repair Go to Step 8
8 Check for proper calibration of the speedometer.
Does the speed indicated on the speed meter closely
match the vehicle speed displayed on the Tech 2?—Go to Step 10Go to Step 9
9 Diagnose and repair the inaccurate speedometer
condition as necessary. Refer to Vehicle Speed
Sensor in Electrical Diagnosis.—Veri fy repai r—
10 Check for proper calibration of the fuel gauge.
Was a problem found? —Verify repair Go to Step 11
11 Check the torque converter clutch (TCC) for proper
operation (if A/T model). If a problem is found, repair
as necessary.
Was a problem found?—Verify repair Go to Step 12
12 1. Using the Tech 2, ignition “On” and engine “Off”.
2. Monitor the “Neutral Switch” in the data display.
Does the Tech 2 indicate correct “Neutral Switch”
status depending on any shift positions?
If a problem is found, repair as necessary.
Was the problem found?—Verify repair Go to Step 13

6E–410 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
25 Remove the eye bolt with gauze filter from the
injection pump and check for the following conditions.
Objects blocking at the gauze filter. Check for a
condition that causes contaminated fuel, such as
the customer is using an aftermarket fuel filter or
ex tended maintenance interval.
Check for a condition that causes fuel wax ing or
icing, such as the customer is using an incorrect
fuel type in winter season or water mix ed with the
fuel.
If a problem is found, repair as necessary.
Was the problem found?
—Replace the
eye bolt with
gauze filter and
verify repair Go to Step 26
26 Remove the injection nozzles from the engine and
check for the following conditions.
Improper splay condition.
Operating pressure is incorrect.
If a problem is found, repair as necessary.
Was the problem found?
—Replace the
injection nozzle
and verify repair Go to Step 27 Step Action Value(s) Yes No
1st Stage 2nd Sta ge
4JA1-TCApproximatly
19.0 MpaApprox ima tly
33.5 Mpa
4JH1-TCApproximatly
19.5 MpaApprox ima tly
33.8 Mpa

ENGINE MECHANICAL (6VE1 3.5L) 6A-3
General Description
Engine Cleanliness And Care
An automobile engine is a combination of many
machined, honed, polished and lapped surfaces with
tolerances that are measured in the thousandths of a
millimeter (ten thousandths of an inch). Accordingly,
when any internal engine parts are serviced, care and
cleanliness are important. Throughout this section, i
t
should be understood that proper cleaning and
protection of machined surfaces and friction areas is
part of the repair procedure. This is considered
standard shop practice even if not specifically stated.


A liberal coating of engine oil should be applied to
all friction areas during assembly to protect and
lubricate the surfaces on initial operation.

Whenever valve train components, pistons, piston
rings, connecting rods, rod bearings, and
crankshaft journal bearings are removed fo
r
service, they should be retained in order.


At the time of installation, they should be installed
in the same locations and with the same mating
surfaces as when removed.

Battery cables should be disconnected before any
major work is performed on the engine. Failure to
disconnect cables may result in damage to wire
harness or other electrical parts.

The six cylinders of this engine are identified by
numbers; Right side cylinders 1, 3 and 5, Left side
cylinders 2, 4 and 6, as counted from crankshaf
t
pulley side to flywheel side.
General Information on Engine Service
The following information on engine service should be
noted carefully, as it is important in preventing damage
and contributing to reliable engine performance.

When raising or supporting the engine for any
reason, do not use a jack under the oil pan. Due to
the small clearance between the oil pan and the oil
pump strainer, jacking against the oil pan may
cause damage to the oil pick-up unit.

The 12-volt electrical system is capable o
f
damaging circuits. When performing any work
where electrical terminals could possibly be
grounded, the ground cable of the battery should
be disconnected at the battery.


Any time the intake air duct or air cleaner is
removed, the intake opening should be covered.
This will protect against accidental entrance o
f
foreign material into the cylinder which could
cause extensive damage when the engine is
started.
Cylinder Block
The cylinder block is made of aluminum die-cast casting
for 75Vtype six cylinders. It has a rear plate integrated
structure and employs a deep skirt. The cylinder liner is
cast and the liner inner diameter and crankshaft journal
diameter are classified into grades. The crankshaft is
supported by four bearings of which width is differen
t
between No.2, No.3 and No.1, No.4; the width of No.3
bearing on the body side is different in order to suppor
t
the thrust bearing. The bearing cap is made of nodular
cast iron and each bearing cap uses four bolts and two
side bolts.
Cylinder Head
The cylinder head, made of aluminum alloy casting
employs a pent-roof type combustion chamber with a
spark plug in the center. The intake and exhaust valves
are placed in V-type design. The ports are cross-flo
w
type.
Valve Train
Intake and exhaust camshaft on the both side of banks
are driven through an camshaft drive gear by timing
belt. The valves are operated by the camshaft and the
valve clearance is adjusted to select suitable thickness
shim.
Intake Manifold
The intake manifold system is composed of the
aluminum cast common chamber and intake manifold
attached with six fuel injectors.
Exhaust Manifold
The exhaust manifold is made of nodular cast iron.
Pistons and Connecting Rods
Aluminum pistons are used after selecting the grade
that meets the cylinder bore diameter. Each piston has
two compression rings and one oil ring. The piston pin
made of chromium steel is offset 1mm toward the thrus
t
side, and the thrust pressure of piston to the cylinder
wall varies gradually as the piston travels. The
connecting rods are made of forged steel. The
connecting rod bearings are graded for correct size
selection.
Crankshaft and Bearings
The crankshaft is made of Ductile cast-iron. Pins and
journals are graded for correct size selection for thei
r
bearing.
Engine Control Module (ECM)
The ECM location is on the common charmber.

ENGINE MECHANICAL (6VE1 3.5L) 6A-5
3. Trouble In Fuel System
Symptom Possible Cause Action
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 faultyRefer to “Electronic Fuel Injection"
section

4. Engine Lacks Compression
Symptom Possible Cause Action
Engine lacks compression Spark plug loosely fitted Tighten to specified torque
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 or broken 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 gage needle
reaches the maximum level. Note the reading.
9. Repeat the test with each cylinder.
If the compression pressure obtained falls belo
w
the limit, engine overhaul is necessary.
Limit; 1000 kPa (145 psi)

6A-8 ENGINE MECHANICAL (6VE1 3.5L)
Hesitation
Symptom Possible Cause Action
Hesitation on acceleration Throttle Position Sensor adjustment
incorrect Replace throttle valve assembly
Throttle Position Sensor circuit open
or shorted Correct or replace
Excessive play in accelerator linkageAdjust or replace
Mass Airflow Sensor circuit open or
poor connections Correct or replace
Mass Airflow Sensor defective Replace
Intake Air Temperature (IAT) Sensor
circuit open or poor connections Correct or replace
IAT Sensor defective Replace
Hesitation at high speeds
(Fuel pressure too low) Fuel tank strainer clogged Clean or replace
Fuel pipe clogged Clean or replace
Fuel filter clogged Replace
Defective fuel pump system Check and replace
Fuel Pressure Control Valve leaking Replace
Hesitation at high speeds
(Fuel injector not working normally) Power supply or ground circuit for
Multiport Fuel Injection System
shorted or open Check and correct or replace
Fuel Injector defective Replace
Cable of Multiport Fuel Injection
System circuit open or poor
connections Correct or replace

6A-10 ENGINE MECHANICAL (6VE1 3.5L)
Engine Lacks Power
Symptom Possible Cause Action
Trouble in fuel system Fuel Pressure Control Valve not
working normally Replace
Fuel injector clogged Clean or replace
Fuel pipe clogged Clean
Fuel filter clogged or fouled Replace
Fuel pump drive circuit not working
normally Correct or replace
Fuel tank not sufficiently breathing
due to clogged Evaporative Emission
Control System circuit Clean or replace
Water in fuel system Clean
Inferior quality fuel in fuel system Use fuel of specified octane rating
Engine Control Module supplied poor
voltage Correct circuit
Throttle Position Sensor cable broken
or poor connections Correct or replace
Throttle Position Sensor defective Replace
Mass Airflow Sensor not working
normally Replace
Manifold Absolute Pressure Sensor
not working normally Replace
Intake Air Temperature Sensor not
working normally Replace
Engine Coolant Temperature Sensor
circuit open or shorted Correct or replace
Engine Coolant Temperature Sensor
defective Replace
Engine Control Module defective Replace
Trouble in intake or exhaust system Air Cleaner Filter clogged Replace filter element
Air duct kinked or flattened Correct or replace
Exhaust system clogged Correct or replace
Ignition failure ———— Refer to Hard Start Troubleshooting
Guide
Heat range of spark plug inadequateInstall spark plugs of adequate heat
range
Ignition coil defective Replace