Komatsu 170-3 Series, Руководство по ремонту, Страница: 173 / 454

12-112
170-3 SERIES
TROUBLESHOOTING
Confirm recent repair history
Degree of use of machine Operated for long period
Condition of hunting
Occurs at a certain speed range
Occurs at low idling
Occurs even when speed is raised
Occurs on slopes
When fuel tank is inspected, it is found to be empty
Rust, water are found when fuel tank is drained
Leakage from fuel piping
Fuel pump outlet port coupler is pushed, almost no fuel comes out
Fuel pump outlet port coupler is pushed, air comes out together with fuel
When exhaust manifold is touched immediately after starting engine, temperature of some cylinders is low
Engine speed sometimes rises too far
Engine is difficult to stop
Questions
Check items
Inspect fuel filter, strainer directly
When negative pressure at inlet port of fuel pump is measured, it is found to be high
When pressure at outlet port of fuel pump is measured, it is found to vary
When pressure at outlet port of fuel pump is measured, it is found to be low
When temperature of injector of each cylinder is measured, there are some cylinders that are low
When flow of spill fuel is checked visually, it is found to be low
Inspect sensor directly (Output voltage and resistance)
Inspect actuator directly (Resistance and filter for clogging)
Inspect fuel rail actuator screen directly
Inspect timing rail actuator screen directly
T
roubleshooting
Replace Clean Clean Replace Replace Replace Replace Replace Replace Clean
Remedy
Insuf
ficient fuel in tank
Loose piping, fuel filter
, entry of air
Clogged fuel filter
, strainer
Defective fuel pump Defective actuation of fuel rail actuator Defective actuation of timing rail actuator Defective injector Defective injector check ball Cut, worn injector O-ring High resistance, clogged fuel return circuit
Causes
When engine is cranked with
starting motor, and
S-5
➅
S-5 Engine does not rotate smoothly (hunting)
General causes why engine does not rotate smoothly
•
Air in fuel system
• Defective governor mechanism
• Defective HPI sensor
• Defective HPI actuator
• Normal output is not applied
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See Troubleshooting S-6
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