Air By-Pass Valve

Check by-pass valve for leakage at idle. Replace valve if leakage exists. Increase engine speed and close throttle suddenly. If air exhausts through valve at instant throttle is closed, valve is satisfactory.

If air from air pump blows out from valve while engine is idling, valve seat is defective and valve must be replaced. If air from pump blows out continuously from by-pass valve while throttle is accelerated rapidly, the valve is normal. If air does not blow out at this time, diaphragm is defective and valve must be replaced.