Idle Enrichment System Test

Idle Enrichment System

1. Warm engine to normal operating temperature, then remove air cleaner. Do not cap any fittings opened by hose removal as leakage is needed for testing.
2. Disconnect hose from idle enrichment diaphragm at plastic connector and remove connector from hose.
3. Connect 3-4 feet of hose to enrichment diaphragm, then start engine and run at slow idle.
4. Apply vacuum to other end of hose and observe engine speed change. If engine speed changes when vacuum is applied, the idle enrichment system is operating properly. If engine speed does not change when vacuum is applied, replace valve assembly on Holley carburetors, or proceed to steps 5 and 6 if equipped with Carter carburetor.
5. Cover air inlet passage and observe engine speed change. If speed changes, the diaphragm is leaking or the air valve is stuck open. If speed does not change, the air valve is stuck closed.
6. Clean valve and repeat step 4. If not operating properly, replace diaphragm.