Page 792 of 6020
TROUBLESHOOTING 6 – 7
4. Excessive Fuel Consumption
Step Action Value(s) Yes No
1 Was the air cleaner element clogged? — Clean or
replace the air cleaner
element. Go to Step 2
2 Was the air leakage found from the air intake side of
the turbocharger? —
Repair or
replace the air intake side of the
turbocharger. Go to Step 3
3 Was the turbocharger working completely? —
Go to Step 4 Replace the
turbocharger
4 Was there the fuel leakage? — Repair or
replace the fuel leakage part. Go to Step 5
5 Was the compression pressure OK? 3.0 MPa
(31.0 kg/cm2,
441 psi) at 200 rpm
Go to Step 6 Readjust the
valve clearance or replace the cylinder head gasket or
cylinder liner or
piston or piston ring or valve
and valve seat
6 Was the injection nozzle pressure or spray pattern normal? —
Go to Step 7 Replace the
injection nozzle
7 Are any DTC stored? — Go to indicated
DTC Solved
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ISUZU KB P190 2007
Page 809 of 6020

6A – 4 ENGINE MECHANICAL
MAIN DATA AND SPECIFICATIONS
Engine model
Item 4JA1T (L)
4JA1TC
Engine type
Combustion chamber type
Cylinder liner type
Timing gear train system Four-cycle, overhead valve, water cooled
Direct injection
Dry type, chrome plated Gear drive
No. of cylinders-bore × stroke mm (in) 4 – 93 × 92 (3.66 × 3.62)
No. of piston rings Compression ring: 2 / Oil ring: 1
Total piston displacement cm3 (in3)
Compression ratio (to 1) 2,499 (152.4)
18.5
Compression pressure MPa (kg/cm2/psi) 3.0 (31.0/441) – 200 rpm
Engine weight (dry) kg (lb)Approximately 239 (527)
Fuel injection order 1 – 3 – 4 - 2
Fuel injection timing BTDC deg8 -
Specified fuel type
Idling speed rpm
Valve clearances (At cold): Intake mm (in)
Exhaust mm (in)
Intake valves Open at (BTDC) deg
Close at (ABDC) deg
Exhaust valves Open at (BBDC) deg
Close at (ATDC) deg
Fuel system JIS No. 2, DIN/EN590, GB252-1944 Diesel fuel
730 ± 25 (A/C Off)
780 ± 25 (A/C ON)
0.4 (0.016)
0.4 (0.016) 24.5
55.5
54.0
26.0
Injection pump type BOSCH distributor VE type BOSCH distributor VP44 type
Governor type Mechanical (Half all speed
type) Electronically controled
Injection nozzle type
Injection nozzle opening pressure Hole with 5 orifices
MPa (kg/cm2/psi) 1st 19.1 (195 / 2,773) 1st 19.0 (194 / 2,755)
2nd (Reference)
25.5 ∼27.0
(260 ∼275 / 3,702 ∼3,920) 2nd (Reference)
34.0 ∼35.5
(347 ∼362 / 4,936 ∼5,154)
Main fuel filter type
Lubricating system
Lubricating method Cartridge paper element and water separator
Pressure circulation
Specified engine oil (API grade) ISUZU genuine 10W – 30 (API CD of ACEA B2/B3)
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Page 811 of 6020

6A – 6 ENGINE MECHANICAL
MAIN DATA AND SPECIFICATIONS
Engine model
Item 4JH1TC
Engine type
Four-cycle, overhead valve, water cooled
Combustion chamber type Direct injection
Cylinder liner type
Timing gear train system Dry type, chrome plated
Gear drive
No. of cylinders-bore × stroke mm (in) 4 – 95.4 × 104.9 (3.76 × 4.13)
No. of piston rings Compression ring: 2 / Oil ring: 1
Total piston displacement liter
Compression ratio (to 1) 2,999
18.3
Compression pressure MPa (kg/cm2/psi) 3.0 (31.0/441) – 200 rpm
Engine weight (dry) kg (lb)MT: Approximately 249 (549)
AT: Approximately 236 (520)
Fuel injection order 1 – 3 – 4 - 2
Specified fuel type JIS No.2, DIN/EN590, GB252-1944 Diesel fuel
Idling speed rpm
700 ± 25 (A/C OFF)
800 ± 25 (A/C ON)
Valve clearances (At cold): Intake mm (in)
Exhaust mm (in)
Intake valves Open at (BTDC) deg
Close at (ABDC) deg
Exhaust valves Open at (BBDC) deg
Close at (ATDC) deg
Fuel system
Injection pump type 0.4 (0.016)
0.4 (0.016) 24.5
55.5
54.0
26.0
BOSCH distributor VP44 type
Injection nozzle type
Injection nozzle opening pressure
MPa (kg/cm
2/psi) Hole with 5 orifices
1st 19.5 (199/2,828)
2nd (Reference) 34.3 ∼35.8 (350 ∼365/4,980 ∼5,197)
Main fuel filter type
Lubricating system
Lubricating method Cartridge paper element and water separator
Pressure circulation
Specified engine oil (API grade) ISUZU genuine 10W – 30 (API CD of ACEA B2/B3)
Oil pump type
Oil filter type Gear
Cartridge paper element
Oil capacity lit (US/UK gal)
6.2 (1.64/1.36) (For 4
× 2)
7.0 (1.85/1.54) (For 4 × 4)
Oil cooler type W ater cooled
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Page 841 of 6020
6A – 36 ENGINE MECHANICAL
GENERAL DESCRIPTION
RTW 46AMF000401
The 4J series automotive diesel engine has special designed combustion chambers in the piston. This design
provides superior fuel economy over a wide range of driving conditions.
Auto-thermatic pistons with cast steel struts are used to reduce thermal expansion and resulting engine noise when
the engine is cold.
Chrome plated dry type cylinder liners provide the highest durability.
The laminated steel sheet cylinder head gasket is very durable and, to increase the head gasket reliability.
The crankshaft has been tufftrided to provide a longer service life. Because the crankshaft is tufftrided, it cannot be
reground.
The 4JA1T(L) engine is equipped with the BOSCH VE-Type distributor injection pump.
The 4JH1TC and 4JA1TC engine is equipped with the BOSCH VP44-Type distributor injection pump.
The engine is turbocharger equipped.
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ISUZU KB P190 2007
Page 966 of 6020

6C – 2 FUEL SYSTEM
MAIN DATA AND SPECIFICATIONS
Description Item
4JA1T (L) 4JA1TC 4JH1TC
Injection pump type Bosch distributor
VE type Bosch distributor VP44 type
Governor type
Mechanical variable
(Half speed oil pressure) Electrical controled
Timer type
Oil pressure Electrical controled
Fuel feed pump type Vane with input shaft
Injection nozzle type Hole type
Number of injection nozzle orifices 5
Injection nozzle orifices
Inside diameter mm (in) 0.19 (0.0075) 0.17 (0.0067) 0.21 (0.0083)
19.1 (195) 19.0 (194) 19.5 (199) Injection nozzle designed operating
pressure MPa (kg/cm2) 1st
2nd 25.0 (255)
33.5 (328) 33.8 (331)
Main fuel filter type Disposable cartridge paper element
Precautions
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 fo
r
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 “O” 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.
• Adhere to all Notices and Cautions.
NOTE:
Injection nozzle adjustment is possible only on the 4JA1L
engine.
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ISUZU KB P190 2007
Page 973 of 6020

FUEL SYSTEM 6C – 9
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 slowly the fuel filler cap.
NOTE: Be careful not to spouting out fuel because of change
the pressure in the fuel tank.
NOTE: Cover opening of the filler neck to prevent any dust
entering.
3. Jack up the vehicle.
4. Support underneath of the fuel tank with a lifter.
5. Remove the inner liner of the wheel house at rear left side.
6. Remove fixing bolt of the filler neck from the body.
7. Disconnect the quick connector (3) of the fuel tube from the
fuel pipe.
NOTE: Cover the quick connector to prevent any dust entering
and fuel leakage.
NOTE: Refer to “Fuel Tube/Quick Connector Fittings” in this
section when performing any repairs.
8. Remove fixing bolt (1) of the tank band and remove the tank band (2).
9. Disconnect the pump and sender connector on the fuel
pump and remove the harness from weld clip on the fuel
tank.
10. Lower the fuel tank (5).
NOTE: W hen lower the fuel tank from the vehicle, don’t scratch
each hose and tube by around other parts.
Installation
1. Raise the fuel tank.
NOTE: W hen raise the fuel tank to the vehicle, don’t scratch
each hose and tube by around other parts.
2. Connect the pump and sender connector to the fuel pump and install the harness to weld clip on the tank.
NOTE: The connector must be certainly connected against
stopper.
3. Install the tank band and fasten bolt.
Torque N·m (kg·m / lb ft)
68 (6.9 / 50)
NOTE: The anchor of the tank band must be certainly installed
to guide hole on frame.
4. Connect the quick connector of the fuel tube to the fuel pipe and the evapo tube from evapo joint connector.
NOTE: Pull off the left checker on the fuel pipe.
NOTE: Refer to “Fuel Tube/Quick Connector Fittings” in this
section when performing any repairs.
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ISUZU KB P190 2007
Page 974 of 6020
6C – 10 FUEL SYSTEM
5. Install the filler neck to the body with bolt.
6. Install the inner liner of the wheel house at rear left side.
7. Remove lifter from the fuel tank.
8. Lower the vehicle.
9. Tigten the filler cap until at least three clicks.
10. Connect the battery ground cable.
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ISUZU KB P190 2007
Page 984 of 6020
6C – 20 FUEL SYSTEM
020L200017
RTW 46CSH000201
18. Timing Check Hole Cover
1) Remove the timing check hole cover.
2) For ease in reinstalling the injection pump, align the timing mark on the timing gear case cover by turning
the crankshaft using wrench.
And bring the piston in the No.1 cylinder to TDC on the
compression stroke by turning the crankshaft until the
crankshaft pulley TDC line aligned with the timing
mark.
Note:
If the check hole cover is reinstalled with the lock bolt
still in place, the crank pulley will not turn.
6C-7
3) Insert the lock bolt (M6 x 30) into the scissors gear idle
gear “B” fixing hole to prevent the scissors gear from
turning.
29. Injection Pump Bracket
20. Injection Pump
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ISUZU KB P190 2007