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TROUBLESHOOTING & REPAIR
F-32 F-32
RANGER 8
ENGINE THROTTLE ADJUSTMENT TEST (continued)
Oscilloscope Method:
1. Connect the oscilloscope to the 115 VAC
receptacle, according to the manufactur-
er’s instructions. At 3700 RPM, the wave-
form should exhibit a period of 16.2 mil-
liseconds. At 2200 RPM, the waveform
should exhibit a period of 27.3 millisec-
onds. Refer to NORMAL OPEN CIRCUIT
VOLTAGE WAVEFORM (115 VAC SUPPLY)
HIGH IDLE – NO LOAD in this section of
the manual.
2. If either waveform periods is incorrect,
adjust the throttle as follows:
Adjust HIGH IDLE: Use the 3/8” wrench to
turn the spring-loaded adjustment nut.
See Figure F.8 for location of the adjust-
ment nut. Adjust the speed until the period
is 16.2 milliseconds.
Adjust LOW IDLE: First make sure there is
no load on the machine. Set the IDLER
switch to AUTO and wait for the engine to
change to low idle speed. Use the 3/8”
wrench to adjust the solenoid nut, which
changes the amount of throw in the throttle
lever arm. See Figure F.9 for location of the
adjustment nut. Adjust the speed until the
period is 27.3 milliseconds.
Vibratach Method:
1. Place the vibratach as close to the engine
as possible. With the machine case top
removed, the top of the air cleaner is the
best location.
2. Start the engine and observe the whip
handle of the vibratach. At HIGH IDLE
(3700 RPM), the whip handle should
exhibit maximum oscillation. At LOW IDLE
(2200 RPM), the whip handle should
exhibit minimum oscillation. Note that
these are median measurements; vibrat-
ach readings may vary slightly above or
below:
3. If either of the vibratach indications is
incorrect, adjust the throttle as follows:
Adjust HIGH IDLE: Use the 3/8” wrench to
turn the spring-loaded adjustment nut.
See Figure F.8 for location of the adjust-
ment nut. Turn the nut clockwise to
increase HIGH IDLE speed. Adjust the
speed until the vibratach whip handle
exhibits maximum oscillation at 3650 to
3750 RPM.
Adjust LOW IDLE: First make sure that
there is no load on the machine. Set the
IDLER switch to AUTO and wait for the
engine to change to low idle speed. Use
the 3/8” wrench to adjust the solenoid nut,
which changes the amount of throw in the
throttle lever arm. See Figure F.9 for loca-
tion of the adjustment nut. Adjust the
speed until the vibratach whip handle
exhibits minimum oscillation at 2150 to
2250 RPM.