Isuzu NHR 4J Series, Workshop Manual

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00 – 8 SERVICE INFORMATION
Checkpoint Possible cause Correction
Defective regulating valve Repair or replace the regulating valve
Defective delivery valve Replace the delivery valve
Defective timer Repair or replace the timer
Worn cam disc Replace the cam disc
Improper control lever operation Adjust or replace the control lever
Defective injection timing Adjust the injection timing
Repair or replace the injection pump
timer
Weak governor spring Replace the governor spring
Injection pump
Worn plunger Replace the plunger assembly
Compression pressure Blown out cylinder head gasket. Worn
cylinder liner.
Piston ring sticking Replace the related parts
Valve clearance Valve clearance improperly adjusted Adjust the valve clearance
Valve spring Valve spring weak or broken Replace the valve spring
Exhaust system Exhaust pipe clogged Clean the exhaust pipe
Full load adjusting
screw seal Open and improperly set adjusting screw
seal Adjust and reseal the adjusting screw