Engine Does Not Pick Up Smoothly (Follow-Up Is Poor) - Komatsu 170-3 Series Shop Manual

TROUBLESHOOTING
S-3

Engine does not pick up smoothly (follow-up is poor)

General causes why engine does not pick up smoothly
• Insufficient intake of air
• Insufficient supply of fuel
• Defective condition of fuel spray
• Improper fuel used
• Abnormality in fuel control system
• Defective HPI sensor
• Defective HPI actuator
• Normal output is not applied
→ See Troubleshooting S-6
Confirm recent repair history
Degree of use of machine
Engine pick-up suddenly became worse
Non-specified fuel is being used
Replacement of filters has not been carried out according to Operation Manual
Engine oil must be added more frequently
Dust indicator is red
Air breather hole in fuel tank cap is clogged
Rust and water are found when fuel is drained
There is leakage from fuel piping
When engine is cranked
with starting motor, and
When exhaust manifold is touched immediately after starting engine, temperature of some cylinders is low
Color of exhaust gas
Clanging sound is heard from around cylinder head
Noise of interference is heard from around turbocharger
High idling speed under no load is normal, but speed suddenly drops when load is applied
There is hunting from engine (rotation is irregular)
Blow-by gas is excessive
Inspect air cleaner element directly
When turbocharger is rotated by hand, it is found to be heavy
When compression pressure is measured, it is found to be low
Inspect valve clearance directly
When pressure at outlet port of fuel pump is measured, it is found to vary
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 be low
When temperature of injector of each cylinder is measured, there are some cylinders that are low
When intake air pressure (boost pressure) is measured, it is found to be normal
Inspect actuator directly (Resistance and filter for clogging)
Inspect sensor directly (Output voltage and resistance)
Inspect for air leakage
12-110
Operated for long period
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
Blue under light load
Black
Causes
Remedy
S-3
170-3 SERIES