Engine Lacks Output (Or Lacks Power) - Komatsu Galeo PC800-8 Shop Manual

40 Troubleshooting
S-6 Engine lacks output (or lacks power)
General causes why engine lacks output
• Insufficient intake of air
• Insufficient supply of fuel
• Defective spray condition of fuel
• Improper selection of fuel
• There is overheating
→ See "S-14 Coolant temperature becomes too high (Overheating)"
• Controller is controlling in derate mode (limiting injection rate (output)
because of an error in electrical system)
Confirm recent repair history
Degree of use of
Operated for long period
machine
Suddenly
Power was lost
Gradually
Non-specified fuel is being used
Replacement of filters has not been carried out according to Operation and Mainte-
nance Manual
Engine oil must be added more frequently
Dust indicator is red (if indicator is installed)
Air breather hole of fuel tank cap is clogged
Fuel is leaking from fuel piping
Output becomes insufficient after short stop of operation
Black
Color of exhaust gas
Blue under light load
When exhaust manifold is touched immediately after starting engine, temperature of
some cylinders is low
When engine is cranked, interference sound is generated around turbocharger
When engine is cranked, abnormal sound is generated around cylinder head
High idle speed is too low
High idle speed under no load is normal, but speed suddenly drops when load is
applied
Engine does not pick up smoothly and combustion is irregular
There is hunting from engine (rotation is irregular)
Blow-by gas is excessive
Inspect air cleaner directly
Inspect air intake piping directly
When boost pressure is measured, it is found to be low
When compression pressure is measured, it is found to be low
Inspect valve clearance directly
Inspect fuel filter, strainer directly
Inspect feed pump gauze filter directly
Carry out troubleshooting for "Rail Press (Very) Low Error. (*1)". See *1 for failure code
When a cylinder is cut out for reduced cylinder mode operation, engine speed does
not change
Inspect boost pressure sensor mount directly
Carry out troubleshooting for "Chg Air Press Sensor High (Low) Error. (*2)"
See *2 for failure code
Carry out troubleshooting for "Fuel Temp Sensor High (Low) Error. (*3)"
See *3 for failure code
*1: Failure codes [CA559] and [CA2249]
*2: Failure codes [CA122] and [CA123]
*3: Failure codes [CA263] and [CA265]
PC800, 850-8
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Remedy
SEN00795-02
Causes
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