Kohler 11RMY, Service Manual

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TP-5867 11/02 47 Section 6 Component Testing and Adjustment
6.9.3 Hunting/Surging
Often hunting/surging problems thought to be caused
by the governor are actually caused by engine or
carburetor problems.
Check engine speed stability
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 6-16. 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.
4. If the engine speed hunts or surges while the
throttle is held steady, check the carburetor
position and engine operation.
a. Check the 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.
1
2
TP5632721
1. Electronic governor stepper motor
2. Carburetor throttle linkage
3. Carburetor mounting holes
3
Figure 6-16 Stepper Motor and Carburetor
6.9.4 Governor System Operation Test
If the engine continues to operate erratically after the
previous checks, test the governor system operation
using the following procedure.
The procedure is
summarized in the flowchart in Figure 6-18.
Governor System Operation Test Procedure
1. Verify that the carburetor throttle linkage is
connected to the stepper motor as shown in
Figure 6-16.
2. Look for broken or loose wiring or plug connections
if the stepper motor moves erratically. Check the
condition of the throttle linkage, and verify that the
throttle plate closes completely.
3. Check the operation of the stepper motor at
startup.
a. If the throttle moves to the full open throttle
position and then moves to and remains in the
fully closed position, the speed sensor input is
probably missing. Proceed to step 4 to check
the magnetic pickup.
b. If the throttle linkage moves erratically or not at
all at startup, proceed to step 7 to check the
stepper motor and the governor control board.
4. Verify the operation of the sensor by connecting a
voltmeter to the sensor leads. See Figure 6-17.
If the air gap is correct, the voltage should be
1.75 volts AC minimum during engine cranking.
358093-A
P4
MP
MP
13 16
1 2 3 4
5 6 7 8
9
10 11
12
14 15
17 18 19 20
Figure 6-17 Magnetic Pickup Leads