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Home >> Land Rover >> 1995 >> Discovery Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System & Component Testing >> Ignition Systems >> Vacuum Delay Valve >> Valve Air Flow Check
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Valve Air Flow Check

  1. Attach a 9.75-10.25 CUBIC INCH vacuum tank to colored side of valve.
  2. Expose Black side to atmospheric pressure.
  3. Observe vacuum drop. Time required for vacuum to drop from minus 20 In Hg to minus 2 In Hg should be .5 second maximum.
  4. To check vacuum recovery air flow, attach a 22.25-23.25 CUBIC INCH vacuum tank to Black side of valve.
  5. Expose colored side to atmospheric pressure.
  6. Observe vacuum drop. Time required for vacuum to drop from 16 In. Hg to 8 In. Hg will be 4-6 minutes. If delay valve does not comply with any of test results, replace unit.
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