Isuzu KB P190. Manual - part 500

 

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Isuzu KB P190. Manual - part 500

 

 

ENGINE DIAGNOSIS (C24SE) 6-1 

SECTION 6 

ENGINE DIAGNOSIS 

TABLE OF CONTENTS 

PAGE 

Engine Diagnosis ..............................................................................................................  6- 2 

Hard Starting .................................................................................................................  6- 2 

Engine Compression Test Procedure .........................................................................  6-  3 

Rough Engine Idling or Engine Stalling......................................................................  6-  4 

Rough Engine Running ................................................................................................  6-  5 

Hesitation ......................................................................................................................  6-  6 

Engine Lacks Power.....................................................................................................  6-  7 

Engine Noisy .................................................................................................................  6- 8 

Abnormal Noise Due to Hydraulic Lash Adjustor ......................................................  6-  9 

Troubleshooting Procedure.........................................................................................  6-  9 

Abnormal Combustion .................................................................................................  6-11 

Engine Oil Consumption Excessive............................................................................  6-12 

Fuel Consumption Excessive ......................................................................................  6-13 

Oil Problems..................................................................................................................  6-13 

Engine Oil Pressure Check ..........................................................................................  6-13 

Malfunction Indicator Lamp .........................................................................................  6-14 

 

6-2 ENGINE DIAGNOSIS (C24SE) 

Engine Diagnosis 

Hard Starting 

1.Starting Motor Does Not Turn Over 

Trouble Shooting Procedure 
Turn on headlights and starter switch. 

Condition Possible 

cause Correction 

Headlights go out or dim 
considerably 

Battery run down or under 
charged 

Recharge or replace battery 

 

Terminals poorly connected 

Clean battery posts and terminals 
and connect properly 

 

Starting motor coil circuit shorted 

Overhaul or replace 

 

Starting motor defective 

Overhaul or replace 

2.Ignition Trouble - Starting Motor Turns Over But Engine Does Not Start 

Spark Test 

Disconnect a high tension cable from any spark plug. 
Connect the spark plug tester (use commercially 
available tool), crank the engine, and check if a spark is 
generated in the spark plug tester. Before cranking the 
engine, make sure that the spark plug tester is properly 
grounded. To avoid electrical shock, do not touch the 
high tension cable while the engine is running. 

 

 

 

Condition Possible 

cause Correction 

Spark jumps across gap 

Spark plug defective 

Clean, adjust spark gap or replace 

 

Spark plug wire in correct 

Connect properly or replace 

 

Ignition timing incorrect 

Refer to Ignition System 

 

Fuel not reaching fuel injector(s) 
or engine 

Refer to item 3 (Trouble in fuel 
system) 

 

Valve timing incorrect 

Adjust 

 

Engine lacks compression 

Refer to item 4 (Engine lacks 
compression) 

No sparking takes place 

Ignition coil disconnected or 
broken 

Connect properly or replace 

 

Electronic Ignition System with 
module 

Replace 

 

Poor connections in engine 
harness 

Correct 

 

Engine Control Module cable 
disconnected or defective 

Correct or replace 

 

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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