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Throttle Positioner (Modulator) Diaphragm Check

  1. Disconnect vacuum line from diaphragm. Connect a vacuum pump to diaphragm. Apply 19 in. Hg vacuum.
  2. If diaphragm does not respond, or will not hold vacuum, replace diaphragm. If diaphragm responds and holds vacuum, proceed with testing.
  3. Remove vacuum pump from diaphragm. If diaphragm does not return within 5 seconds, replace defective diaphragm. Reconnect vacuum line. If diaphragm returns in 5 seconds, diaphragm is good.
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