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Home >> Honda >> 1990 >> Prelude 2.0 S, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests - CARBURETED >> Emission Systems & Sub-Systems >> Purge Control System >> Purge Control Diaphragm Valve
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Purge Control Diaphragm Valve

  1. With engine coolant temperature less than 145°F (63°C), disconnect No. 19 vacuum hose at purge control diaphragm valve and connect vacuum gauge to hose. See Fig 1 . Start engine and allow to idle. If vacuum is not present, go to next step. If vacuum is present, test purge cut-off solenoid valve. See PURGE CUT-OFF SOLENOID VALVE  under EMISSION SYSTEMS & SUB-SYSTEMS in this article.
  2. Start engine and warm to normal operating temperature (cooling fan comes on). Jack up front of vehicle and support with safety stands. Block rear wheels and set parking brake. Place selector lever in the "2" position or 2nd gear and raise engine speed to 3500 RPM. Vacuum should be present. If so, valve is okay. If vacuum is not present, test purge cut-off solenoid valve. See PURGE CUT-OFF SOLENOID VALVE  under PURGE CONTROL SYSTEM in this article.
    Fig 1: Testing Purge Control Diaphragm Valve
    G117946Courtesy of AMERICAN HONDA MOTOR CO., INC.