Single Diaphragm Valve
- Check all vacuum hoses for correct routing. Warm engine to operating temperature. Disconnect vacuum hose from EGR valve.
- 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.
- 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.