Isuzu KB P190. Manual — part 342

6A-8 ENGINE MECHANICAL (4JK1/4JJ1)

Trouble Shooting

Engine does not turn over

Condition Possible

Cause Correction

Dead or weak battery

Charge battery

Replace battery

Incomplete circuit

Connect

Repair

Starter motor brushes stuck, worn,
or broken

Replace brushes

Starter motor does not rotate

Starter motor internal damage

Repair motor

Ring gear abrasion

Replace ring gear

Starter motor not meshed with
flywheel

Magnetic switch (starter motor) not
properly adjusted

Adjust

Dead or weak battery

Charge battery

Replace battery

Insufficient contact pressure
between starter motor brushes and
commutator

Adjust pressure

Armature (starter motor) stuck

Repair armature

Starter motor pinion meshed with
ring gear but does not rotate

Engine internal damage (Seizure)

Repair engine

Engine turns over but does not start

Condition Possible

Cause Correction

Air in fuel system

Bleed air from fuel system

Air entering fuel pipe

Replace pipe and bleed air from
fuel system

Empty fuel tank

Replenish fuel

Clogged strainer (fuel suction)

Clean or replace strainer

Clogged fuel pipe

Clean or replace pipe

Feed pump malfunction

Replace pump

Use of wrong fuel for prevailing
temperatures

Drain existing fuel and replace with
appropriate fuel

Fuel is not delivered to fuel supply
pump

Clogged fuel filter

Replace filter

Loose injection pipe connections

Tighten connections

Loose or broken electrical
connectors

Tighten and/or replace connectors

Bad rotational sensor

Replace sensor

Fuel is delivered to fuel supply
pump

Engine control system malfunction

System diagnosis

Air in fuel system

Bleed air from fuel system

Feed pump malfunction

Repair pump

Loose or broken electrical
connectors

Tighten and/or replace connectors

Clogged fuel filter

Replace filter

Insufficient or unstable fuel delivery
volume

Engine control system malfunction

System diagnosis

ENGINE MECHANICAL (4JK1/4JJ1) 6A-9

Excessive black exhaust smoke

Condition Possible

Cause Correction

Bad injection timing

Engine control system malfunction

System diagnosis

Carbon deposit at nozzle tip

Clean fuel injector assembly

Sticking nozzle

Replace fuel injector assembly

Bad fuel injector condition

Engine control system malfunction

System diagnosis

Excessive valve clearance

Adjust clearance

Sticking valve stem (valve open)

Repair or replace valve

Damaged valve spring

Replace spring

Valve seat abrasion

Repair valve seat

Compression leakage due to
damaged piston ring

Replace piston ring

Damaged gasket

Replace gasket

Insufficient compression pressure

Piston scoring

Replace piston

Water in fuel

Drain existing fuel and replace with
new fuel

Fuel condition

Poor fuel quality

Drain existing fuel and replace with
new fuel

Clogged intake pipes

Clean or replace pipes

Poor engine aspiration

Clogged air cleaner element

Clean or replace element

Defective sensor

Replace sensor

Malfunction detected by engine
control system

Engine control system malfunction

System diagnosis

Intake throttle valve sticking

Repair or replace valve

EGR valve sticking

Repair or replace valve

EGR valve and/or intake throttle
valve malfunction

Engine control system malfunction

System diagnosis

Damaged turbocharger blade

Replace turbocharger

Rough turbocharger shaft rotation

Replace turbocharger

Oil leakage from oil seal

Replace turbocharger

Turbocharger malfunction

Broken actuator

Replace turbocharger

6A-10 ENGINE MECHANICAL (4JK1/4JJ1)

Excessive white exhaust smoke

Condition Possible

Cause Correction

Bad injection timing

Engine control system malfunction

System diagnosis

Defective sensor

Replace sensor

Control unit malfunction

Replace unit

Malfunction detected by engine
control system

Engine control system malfunction

System diagnosis

Excessive valve clearance

Adjust clearance

Sticking valve stem (valve open)

Repair or replace valve

Damaged valve spring

Replace spring

Valve seat abrasion

Repair valve seat

Compression leakage due to
damaged piston ring

Replace piston ring

Damaged gasket

Replace gasket

Insufficient compression pressure

Piston scoring

Replace piston

Fuel condition

Water in fuel

Drain existing fuel and replace with
new fuel

Worn or damaged piston ring(s)

Replace ring(s)

Defective valve stem oil seal

Replace oil seal

Defective turbocharger oil seal

Replace turbocharger

Excessive oil consumption

Clogged turbocharger oil return
pipe

Repair pipe

Engine knocking

Condition Possible

Cause Correction

Bad timing

Engine control system malfunction

System diagnosis

Defective sensor

Replace sensor

Control unit malfunction

Replace unit

Malfunction detected by engine
control system

Engine control system malfunction

System diagnosis

Fuel condition

Poor quality fuel

Drain existing fuel and replace with
new fuel

Clogged air cleaner element

Clean or replace element

Clogged intake pipes

Clean or replace pipes

Poor engine aspiration

Engine control system malfunction

System diagnosis

Foreign material in cylinders

Engine overhaul

Engine break-down

Scored pistons and/or bearings

Replace pistons and/or bearings

ENGINE MECHANICAL (4JK1/4JJ1) 6A-11

Abnormal engine rotation

Condition Possible

Cause Correction

Defective control unit

Replace unit

Engine speed cannot be increased

Engine control system malfunction

System diagnosis

Defective control unit

Replace unit

Engine control system malfunction

System diagnosis

Clogged fuel filter element

Replace element

Defective fuel injector(s)

Replace fuel injector assembly

Water in fuel

Drain existing fuel and replace with
new fuel

Engine speed unstable

Air in fuel system

Bleed air from fuel system

Damaged turbocharger fan

Replace turbocharger

Rough turbocharger shaft rotation

Replace turbocharger

Turbocharger malfunction

Broken actuator

Replace turbocharger

Abnormal battery charging

Condition Possible

Cause Correction

Open or shorted wiring and/or
connectors

Repair or replace wiring and/or
connectors

Defective generator

Repair or replace generator

No charging

Defective battery

Replace battery

Open or shorted wiring and/or
connectors

Repair or replace wiring and/or
connectors

Defective generator

Repair or replace generator

Loose generator drive belt

Adjust belt tension or replace belt

Insufficient charging

Defective battery

Replace battery

Shorted wiring

Repair or replace wiring

Defective generator

Repair or replace generator

Excessive charging

Defective battery

Replace battery