Electronic Governor; Governor Checks - Kohler COM7.5 Service Manual

The microprocessor controller monitors the DC output
voltage. To verify accurate voltage control, increase and
decrease loads while measuring DC output voltage at
the output connector. The output voltage should remain
fairly steady at the rated voltage as the engine speed
increases or decreases in response to load changes.
If voltage falls below the rated value as load increases or
decreases, check for the following problems:
D
Inadequate fuel supply
D
Fuel solenoid malfunction
D
Fuel metering valve malfunction
D
Stepper motor/throttle linkage binding

4.2 Electronic Governor

The system uses a variable-speed generator to
maintain the rated output voltage with varying loads.
The governor system regulates the engine speed with
changing loads.
The governor system consists of an electronic governor
control and an electromechanical actuator. Leads AC1
and AC2 provide a speed (frequency) signal from the AC
side of the voltage rectifier to the control board. The
control board signals the actuator, which controls the
throttle and hence the engine speed, to maintain the
generator nominal output voltage.
4.2.1

Governor Checks

The factory-set electronic governor does not normally
require adjustment. If the engine operates erratically,
check the following connections and conditions before
adjusting the governor:
D
Check the electrical connections and wire harnesses
for clean, tight connections.
D
Check the speed-sensing connections at rectifier AC
terminals 2 and 3. Poor connections may cause an
erratic signal, which could cause the unit to shut
down.
D
Check the electrical ground connections.
24 Section 4 Component Testing and Adjustment
D
Check the battery connections.
connections are clean and tight.
D
Check for a good positive 12-volt DC supply.
D
Check for stepper motor/throttle shaft linkage binding
or wear. The linkage arm and lever arms must not
bind or rub against other components while moving.
D
Verify that the governor stepper motor operates with
steady and smooth movement. If the movement of
the stepper motor is erratic or large changes in
movement occur, check for shaft misalignment,
linkage binding, or loose or broken wiring or plug
connections.
D
Check the carburetor
misadjustment. Check the idle-adjustment screw.
The screw should not prevent the throttle plate from
completely closing. Also, check the throttle linkage
for any binding, dirt, damage, etc.
Note: Often hunting/surging problems thought to be
caused by the governor are actually linked to
carburetor adjustment.
adjustment before adjusting the governor.
1. Governor stepper motor
Figure 4-2 Governor Location
Verify that the
for dirt, grime, or
Check the carburetor
1
photos3-6
TP-6120 5/02