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Single Diaphragm Valve

  1. Check all vacuum hoses for correct routing. Warm engine to operating temperature. Disconnect vacuum hose from EGR valve.
  2. With engine at idle, apply intake manifold vacuum to EGR valve. On systems equipped with a modulator and/or auxiliary control valve, engine should run rough or carburetor should make bubbling noise.
  3. On systems not equipped with a modulator and/or auxiliary control valve, increase engine speed to 3000-3500 RPM. Carburetor should make bubbling noise. If bubbling noise is not heard, check other EGR system controls. See appropriate article.
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