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Home >> Geo >> 1990 >> Tracker Base, Automatic >> Repair and Diagnosis >> Engine Performance >> Engine Controls - Adjustments >> Ignition Timing >> Advance Timing >> Vacuum Advance
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Vacuum Advance

  1. Remove vacuum hose from vacuum advance outer diaphragm connector and attach hand-held vacuum pump. Apply 15 in. Hg of vacuum while observing base plate.
  2. Base plate should move smoothly and vacuum pump indicator gauge should remain constant. Check inner diaphragm unit in same manner. If vacuum advance performance is incorrect, check vacuum advance unit and distributor plate for sticking or worn linkage. Replace as necessary.
PICK-UP COIL AIR GAP (1)

Application Clearance In. (mm)
All Models .008-.016 (.20-.41)
(1) Same as crank angle sensor air gap.