Anti-Backfire Valve Test

Operate engine until it reaches normal operating temperature. Inspect all hoses and hose connections for obvious leaks and correct as necessary before checking anti-backfire valve operation. Accelerate engine, in neutral. Allow throttle to close rapidly. Valve is operating satisfactorily when no, or few, exhaust system backfire occurs. If a further check is necessary, disconnect air hose to intake manifold at anti-backfire valve. Insert a suitable plug in hose and fasten it securely. Open and close throttle rapidly, if air flow is felt for 1-2 seconds (240Z) or 2-3 seconds (all others) by a finger at valve outlet to intake manifold, valve is functioning properly. If air flows continuously for a longer period, valve should be replaced. Connect air hose to intake manifold and disconnect air inlet hose from air pump at anti-backfire valve. If engine idle speed changes excessively, valve function is improper and should be replaced.