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F-21

F-21

TROUBLESHOOTING & REPAIR

ENGINE THROTTLE ADJUSTMENT TEST (continued)

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FIGURE F.5 – HIGH IDLE ADJUSTMENT

THROTTLE LINKAGE

3/8" HIGH IDLE ADJUSTMENT NUT

CHOKE CABLE

FIGURE F.6 – LOW IDLE ADJUSTMENT

7/16" LOW IDLE ADJUSTMENT NUT

SOLENOID

HOUSING

MUFFLER

ROD

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Frequency Counter Method

1.Plug the frequency counter into one of the 120 VAC auxiliary receptacles.

2.Start the engine and check the frequency counter. At HIGH IDLE (3700 RPM), the counter should read between 61 and 63 Hz. At LOW IDLE (2400 RPM), the counter should read between 39 and 40 Hz. Note that these are median measurements; hertz readings may vary slightly above or below.

3.If either of the readings is incorrect, adjust the throttle as follows:

Adjust HIGH IDLE: Use the 3/8" wrench to loosen the spring-loaded adjustment nut. See Figure F.5 for location of the adjustment nut. Turn the nut clockwise to increase the HIGH IDLE speed. Adjust the speed until the fre- quency reads between 61 and 63 Hz.

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 7/16" wrench to adjust the solenoid nut, which changes the amount of throw in the throttle lever arm. See Figure F.6 for the location of the adjustment nut. Adjust the nut until the frequency reads between 39 and 40 Hz.

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RANGER 250

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Lincoln Electric SVM150-A service manual Figure F.5 High Idle Adjustment, Frequency Counter Method