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Throttle Body Adjustment

CAUTION: Throttle limiting (stop) screw is set by manufacturer and should NOT be moved. If screw is accidentally turned, perform throttle body adjustment.
  1. Disconnect vacuum hose from throttle valve purge control fitting. Attach hand-held vacuum pump to fitting. Start engine and let it idle. At idle, vacuum reading should be 0-1 in. Hg (preferably zero).
  2. If vacuum reading exceeds 1 in. Hg or if adjustment screw has been tampered with, loosen lock nut and turn throttle stop screw until there is a gap between stop lever and screw.
  3. Turn in stop screw until it just touches lever. Place a thin piece of paper between stop screw and lever. Slide paper back and forth until resistance is felt. The stop point will become obvious. After determining stop point, turn stop screw in 1/2 turn. Tighten lock nut.
  4. Check vacuum reading once again and repeat adjustment if necessary. If adjustment is correct, apply paint to stop screw and lock nut. Check idle switch and idle speed and mixture adjustment.
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