Isuzu NHR 4J Series, Workshop Manual

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SERVICE INFORMATION 00 – 9
4. EXCESSIVE FUEL CONSUMPTION
Checkpoint Possible cause Correction
Fuel system Fuel leakage Repair or replace the fuel system
related parts
Air cleaner Clogged air cleaner element Clean or replace the air cleaner
element
Idling speed Poorly adjusted idling speed Adjust the idling speed
Injection nozzle Injection nozzle injection starting pressure
too low
Improper spray condition Adjust or replace the injection nozzle
Fuel injection timing Fuel injection timing improperly Adjust the fuel injection timing
Injection pump Defective Delivery valve resulting is fuel
drippage after fuel injection Replace the delivery valve
Valve clearance Valve clearance improperly adjusted Adjust the valve clearance
Compression pressure Blown out cylinder head gasket. Worn
cylinder liner.
Piston ring sticking Replace the related parts
Valve spring Valve spring weak or broken Replace the valve spring
5. EXCESSIVE OIL CONSUMPTION
Checkpoint Possible cause Correction
Engine oil Engine oil unsuitable
Too much engine oil Replace the engine oil
Correct the engine oil level
Oil seal and gasket Oil leakage from the oil seal and/or the
gasket Replace the oil seal and/or the gasket
Air breather Clogged air breather Clean the air breather
Intake and exhaust
valve Worn valve stems and valve guides Replace the intake and exhaust
valves and the valve guides