Isuzu D-Max / Isuzu Rodeo (TFR/TFS). Manual - part 781

6A–4

ENGINE MECHANICAL (6VD1 3.2L)

Engine Diagnosis

Hard Starting

1. Starting Motor Does Not Turn Over
Troubleshooting 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

considerably

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 an ignition coil from any spark plug. Connect
the spark plug tester 5–8840–0383–0, start the engine,
and check if a spark is generated in the spark plug tester.
Before starting the engine, make sure that the spark plug

tester is properly grounded. To avoid electrical shock, do
not touch the part where insulation of the ignition coil is
broken while the engine is running.

Condition

Possible cause

Correction

Spark jumps across gap

Spark plug defective

Clean, adjust spark gap 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

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

occurs but engine does not start.

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

6A–5

ENGINE MECHANICAL (6VD1 3.2L)

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

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 below the
limit, engine overhaul is necessary.

Limit; 1000 kPa (145 psi)

6A–6

ENGINE MECHANICAL (6VD1 3.2L)

Rough Engine Idling or Engine Stalling

Condition

Possible cause

Correction

Trouble in fuel injection system

Idle air control valve defective

Replace

Throttle shutting off incomplete

Correct or replace

Throttle position sensor circuit open
or shorted

Correct or replace

Fuel injector circuits open or shorted

Correct or replace

Fuel injectors damaged

Replace

Fuel pump relay defective

Replace

Mass Airflow Sensor circuit open or
poor connections

Correct or replace

Mass Airflow Sensor defective

Replace

Manifold Absolute Pressure Sensor
circuit open or poor connections

Correct or replace

Manifold Absolute Pressure Sensor
defective

Replace

Engine Coolant Temperature Sensor
circuit open or poor connections

Correct or replace

Engine Coolant Temperature Sensor
defective

Replace

Intake Air Temperature sensor circuit
open or poor connections

Correct or replace

Intake Air Temperature sensor
defective

Replace

Vehicle Speed Sensor circuit open or
shorted

Correct or replace

Vehicle Speed Sensor defective

Replace

Trouble in emission control system

Engine Control Module defective

Replace

Canister purge valve circuit open or
poor connections

Correct or replace

Canister purge valve defective

Replace

Evaporative Emission Canister
Purge control valve defective

Replace

Trouble in ignition system

Refer to “Hard Start”

Others

Engine lacks compression

Refer to “Hard Start”

Valve incorrectly seated

Lap valve

Air Cleaner Filter clogged

Replace filter element

Valve timing incorrect

Readjust

Idle air control valve broken

Replace

Fast idle solenoid defective

Replace

Positive Crankcase Ventilation valve
defective or clogged

Replace

6A–7

ENGINE MECHANICAL (6VD1 3.2L)

Rough Engine Running

Condition

Possible cause

Correction

Engine misfires periodically

Ignition coil layer shorted

Replace

Spark plugs fouling

Clean or install hotter type plug

Spark plug(s) insulator nose leaking

Replace

Fuel injector(s) defective

Replace

Engine control module faulty

Replace

Engine knocks periodically

Spark plugs running too hot

Install colder type spark plugs

Engine control module faulty

Replace

Engine lacks power

Spark plugs fouled

Clean

Fuel injectors defective

Replace

Mass Airflow Sensor or Intake
Airflow Sensor circuit defective

Correct or replace

Barometric Pressure (BARO)
Sensor or Barometric Pressure
Sensor circuit defective

Correct or replace

Engine Coolant Temperature Sensor
or Engine Coolant Temperature
Sensor circuit defective

Correct or replace

Engine Control Module faulty

Replace

Intake Air Temperature Sensor or
Intake Air Temperature Sensor
circuit defective

Correct or replace

Throttle Position Sensor or Throttle
Position Sensor circuit defective

Correct or replace