Engine Speed Is Unstable Or Engine Hunts - Komatsu PC130-7 Shop Manual

TROUBLESHOOTING
E-3 Engine speed is unstable or engine hunts
(1) Low idling speed is unstable.
Trouble (2) Engine hunts.
(3) High idling speed is low.
• Since the governor and pump controller normally performs the following controls, the set opening angle
of the fuel control dial does not always conform accurately to the control angle of the governor motor.
1) Governor control by selecting working mode
2) Governor control by setting automatic decelerating function
3) Governor control according to operating condition of control lever
4) Governor control by automatic warm-up function in cold state
Related
5) Governor control by turbocharger protecting function when engine is started
information
Accordingly, when checking the operation of the fuel control dial and governor motor, be sure to select
GOVERNOR ADJUSTMENT FUNCTION [03]. (Since the governor control function does not operate
in this mode, the set opening angle of the fuel control dial always conforms to the control angle of the
governor motor.)
• The engine speed can be checked with the monitoring function.
(Code: 010, by 10 rpm)
Defective governor
1 potentiometer
(Internal defect)
Defective adjustment of
2
governor lever
Malfunction of governor
3
motor
Possible causes
and standard
value in normal
Defective fuel control
4
state
system of engine
Disconnection in wiring
harness
5 (Disconnection in wiring
harness or defective con-
tact in connector)
Short circuit with chassis
ground in wiring harness
6
(Contact with ground
circuit)
Defective governor and
7
pump controller
20-410
(1)
Cause Standard value in normal state/Remarks on troubleshooting
aTurn starting switch ON and carry out troubleshooting (monitoring).
Monitoring code
If the monitoring display is abnormal, carry out troubleshooting for error
code [217].
See TESTING AND ADJUSTING, Special functions of monitor panel.
aTurn starting switch ON or start engine and carry out troubleshooting.
When the following operation is performed, if the governor motor lever
moves smoothly, the governor motor is normal.
• Operate the fuel control dial between low idling and high idling.
• Stop the engine by turning the starting switch OFF.
See the Shop Manual for 95-3 Seriese, Engine.
aPrepare with starting switch OFF, then carry out troubleshooting with-
out turning starting switch.
Wiring harness between C01 (female) (23) and
J07 and H15 (female) (5)
aPrepare with starting switch OFF, then carry out troubleshooting with-
out turning starting switch.
Between C01 (female) (23) – J07 – H15
(female) (5) or other related circuit wiring har-
ness and chassis ground
Troubleshooting cannot be carried out since the defect is in the gover-
nor and pump controller (If none of causes 1 – 6 is the cause of the trou-
ble, the governor and pump controller is defective).
Item
002
Governor and pump
controller model code
003
E-3
Normal display
130
Max. 1 z
Resistance
Min. 1 z
Resistance
PC130-7