Governor System/Magnetic Pickup Operation Test; Hunting/Surging - Kohler 8.5RES Service

6.9.3

Hunting/Surging

Often hunting/surging problems thought to be caused
by the governor are actually caused by engine or
carburetor problems.
using the following procedure before testing the
governor.
1. Open the generator set line circuit breaker.
2. Start the generator set.
3. Hold the throttle linkage steady while the engine is
running. See Figure 6-20. If the engine runs at a
steady speed with no hunting or surging when the
throttle is held steady, then the hunting/surging
problems during operation are probably caused by
the governor. Proceed to Section 6.9.4.
1. Electronic governor stepper motor
2. Carburetor throttle linkage
3. Carburetor mounting holes
Figure 6-20 Stepper Motor and Carburetor
Check the magnetic pickup. See steps 4--6.
Check the magnetic pickup connections to the controller:
P1-17, P1-18, and P1-29.
Figure 6-21 Governor System Operation Test Procedure Summary (Section 6.9.4)
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Check engine speed stability
1
2
Check that the carburetor throttle linkage
is connected to the stepper motor as
shown in Figure 6-20.
Check for broken or loose wiring or
connections and other items in step 2.
Check stepper motor operation at startup.
Does it move to fully open and then move
to and stay in the fully closed position?
Yes
See step 3.
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4. If the engine speed hunts or surges while the
throttle is held steady, check the carburetor
position and engine operation.
a. Check carburetor position. Slotted mounting
holes in the base of the carburetor determine
the carburetor position, which affects the
throttle operation. Verify that the carburetor is
mounted as close to the governor actuator
(stepper motor) as the mounting holes allow.
b. Refer to the engine service manual for other
engine diagnostic and service information.
6.9.4 Governor System/Magnetic
Pickup Operation Test
If the engine continues to operate erratically after the
previous checks, test the governor system operation
using the following procedure.
summarized in the flowchart in Figure 6-21.
3
TP5632721
Disconnect the magnetic pickup and check the stepper
motor operation again. See steps 7--9.
Check the stepper motor connections to the controller.
See step 10.
Check the stepper motor coils. See step 11.
Troubleshoot the controller. See step 12.
The procedure is
No
Section 6 Component Testing and Adjustment
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