Isuzu 2008MY N Series Workshop Manual page 363

1A-360 Engine Control System (4HK1)
Checks
Fuel System Checks
Air Intake System Checks
Exhaust System Checks
Engine Mechanical Checks
Additional Checks
Inspect the fuel system for the following conditions. Refer to Fuel System
Check chart and appropriate procedure in Section 1D Engine Fuel.
• Air in the fuel system.
• Water contamination in the fuel.
• Fuel waxing or icing.
• Fuel filter clogging.
• External fuel leaks or high engine oil level.
• Fuel leak off from the fuel pressure limiter valve and fuel injectors.
• Fuel lines between the fuel tank and fuel supply pump for being crushed,
kinked, tightness, cracks and plugged.
• A plugged fuel tank vent hose.
• Inside the fuel tank for any foreign material that may be getting drawn into
the fuel line pickup causing a blocked condition.
• Fuel supply pump operation.
Notice: The fuel supply pump must be timed to the engine and adjustment
value must be learned to the ECM.
• Perform the Cylinder Balance Test with a scan tool.
• Perform the Injector Force Drive with a scan tool.
• Observe the Fuel Compensation for each cylinder at idle on the scan tool.
Inspect the air intake system for the following conditions.
• Air cleaner, air intake ducts and charge air cooler for a restriction, holes, or
leaks.
• A restriction in the turbocharger inlet duct.
• Intake throttle valve for a stuck condition.
• A restriction or leak in the intake manifold.
• A worn or damaged turbocharger turbine wheel, shaft or compressor
wheel. Refer to Turbocharger Assembly in Section 1J Induction.
• Turbocharger nozzle control solenoid for a stuck condition. Refer to
Turbocharger Assembly in Section 1J Induction.
Inspect the exhaust system for a possible restriction. Refer to Exhaust System
in Section 1G Engine Exhaust.
Inspect the engine mechanical for the following conditions. Refer to the
Section 1B Engine Mechanical.
• Poor cylinder compression.
• Improper valve gap.
• Broken or weak valve springs.
• Worn camshaft lobes.
• Inspect the EGR system operating correctly. Refer to EGR Control System
Check in this section.
• Inspect for an engine overheat condition. Refer to Cooling System in
Section 1C Engin Cooling.
• Inspect the A/C operation.
• Inspect the lock up clutch operation. (Smoother only)
Action