Air Pump & Relief Valve
- Check air pump drive belt adjustment. Belt is adjusted properly if it can be deflected 3/4-1" midway on its longest run. Disconnect air pump output hose and connect a pressure gauge to hose. Start and allow engine to idle at 850 RPM. Check pressure gauge reading.
- Air pump pressure should be at least 1.0-1.5 psi (.07-.11 kg/cm2
). If not, pump is defective and must be replaced. Increase engine speed and note pressure at which pressure relief valve opens the excess pump pressure. Relief valve should relieve pressure at 5.8-8.0 psi (.39-.56 kg/cm2
) on Midget or 4.5-6.5 psi (.32-.45 kg/cm2
) on MGB. If not, replace pressure relief valve.NOTE: A faulty air injection pump is usually indicated by excessive air pump noise.