5.6
Section 5
Fuel System and Governor
Figure 5-5. Carburetor Adjustment Locations.
Low Idle Fuel Adjustment
NOTE:
Engines will have fixed low idle or limiter
caps on the two idle fuel adjusting needles.
Step 3 can only be performed within the
limits allowed by the cap. Do not attempt to
remove the limiter caps.
1. Start the engine and run at half throttle for 5 to
10 minutes to warm up. The engine must be
warm before doing steps 2, 3, and 4.
2. Place the throttle control into the
idle
or
slow
position. Adjust the low idle speed to 1200 RPM.
Follow the Adjusting the Low Idle Speed (RPM)
procedure.
3.
Low Idle Fuel Needle(s) Setting:
Place the
throttle into the
idle
or
slow
position.
a. Turn one of the low idle fuel adjusting
needles out (counterclockwise) from the
preliminary setting until the engine speed
decreases (rich). Note the position of the
needle. Now turn the adjusting needle in
(clockwise). The engine speed may increase,
then it will decrease as the needle is turned
in (lean). Note the position of the needle. Set
the adjusting needle midway between the
rich and lean settings. See Figure 5-6.
b. Repeat the procedure on the other low idle
adjustment needle.
4. Recheck/adjust the Low Idle Speed (RPM) to the
specified setting.
Figure 5-6. Optimum Low Idle Fuel Settings.
Governed Idle System
A governed idle control system is used to maintain a
desired idle speed regardless of ambient conditions
(temperature, parasitic load, etc.) that may change.
An outer secondary spring connected between the
governor lever and the governed idle adjuster on the
main bracket establishes the governed idle speed. See
Figure 5-7.
Governed Idle Speed Adjustment
1. Make sure the governed idle spring is in the outer
hole in the governor lever and the hole in the
governed idle (outer) adjuster. See Figure 5-7.
2. Make sure the governor spring is in the inner slot
of the governor lever and the hole in the high
speed (inner) adjuster. See Figure 5-7. Pull the
governor lever
away
from carburetor to the limit
of its travel and check that the governor spring is
loose and not under any tension. See Figure 5-8.
Turn the high-speed (RPM) adjustment screw
counter-clockwise (if required) until spring is
loose.
Figure 5-7. Governor Springs Installed.
Lean
Rich
Adjust to
Midpoint
Lean
Rich
Adjust to
Midpoint
Left Side
Right Side
Low Idle Fuel Adjusters
(with Limiters)
Low Idle
Speed (RPM)
Adjustment
Screw
Bowl
Vent
Governed Idle
Spring
Governor
Spring
