Mixture Control Valve System

Mixture Control Valve w/Filter:

MIXTURE CONTROL VALVE CHECK

1. Start engine and idle.
2. Disconnect manifold vacuum hose to mixture control valve, at valve, and pinch hose closed with suitable pliers.
3. Wait a few seconds, then re-connect vacuum hose and release pliers. The engine should stumble for a few seconds then return to normal idle.
4. If there is no change, remove valve.
5. Try to blow air through valve, no air should flow.
6. While blowing into valve, apply vacuum suddenly to vacuum port using a vacuum pump. Air should flow through valve for a few seconds, then stop.
7. Check for vacuum leak from diaphragm by applying vacuum with a vacuum pump. When vacuum is first applied, vacuum pump gauge may show a slight drop and then hold stable vacuum over time. This is normal. If vacuum bleeds down over time (vacuum continues to drop after 5 seconds), then diaphragm is leaking and valve should be replaced.