8-5
Throttle Body / Governor Actuator
The throttle body and governor actuator are one as-
sembly (Figures 8-4 and 8-5). The throttle plate is
mounted on the same ball bearing-mounted shaft
as the actuator rotor. The actuator stator is ener-
gized by a pulse width modulated signal from the
genset controller, which monitors frequency and re-
calculates the pulse width—and therefore throttle
position—necessary to maintain rated frequency as
load varies. The torsion spring opposes the rotor.
Do not attempt to readjust the idle screw (Fig-
ure 8-5), which was set and sealed at the factory.
Checking Throttle Plate Action: If the genset
does not start, remove the air filter and observe the
throttle plate while cranking. The throttle plate
should close against the idle stop when deener-
gized, open fully while cranking and modulate
smoothly while running. If the throttle does not func-
tion, connect its terminals to a 12 volt battery with
jumpers. If the throttle opens fully, the problem is
probably in the control circuit, not the throttle body.
Checking Stator Winding Continuity: If the
throttle does not open, disconnect the wiring at the
stator terminals, check for electrical resistance and
replace the stator is not between 4.5 and 5.5 ohms.
Replacing Stator: To remove the stator assembly
from the throttle body, remove the snap-on cover,
torsion spring and the four mounting screws. When
reassembling, make sure that the mating bosses
are properly aligned before tightening the four stator
screws. Torque the four stator screws to 18 lb-in
(2 N-m). Then press the torsion spring onto the flat
on the end of the throttle shaft and catch the spring
hook in the slot in the coil bobbin (Figure 8-4).
Replacing Throttle Body: Replace the throttle
body if there is any looseness, play or binding in the
throttle shaft or if the factory seal on the idle screw
has been broken. When pressing the rotor and
retention ring onto the shaft of the throttle body, sup-
port the end of the shaft as shown (Figure 8-5) to
avoid damage to the bearings and throttle plate.
Then assemble stator, torsion spring, snap-on cov-
er and dust cap to the body.
TORSION
SPRING
SNAP-ON
COVER
HOOK
SPRING
HERE
FIGURE 8-4. THROTTLE BODY / GOVERNOR AC-
TUATOR
SUPPORT END OF SHAFT
HERE WHEN PRESSING ON
ROTOR AND RETENTION RING
STATOR
ROTOR
RETENTION
RING
THROTTLE
SHAFT
THROTTLE
BODY
IDLE SCREW
(FACTORY ONLY)
PERMANENT
MAGNET
ROTOR
DUST CAP
FIGURE 8-5. ACTUATOR ROTOR & STATOR
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