Check & Relief Valve
- Remove check valve and inspect for leakage by blowing air into ports in the check valve. When air is applied from the fuel tank side, the check valve is normal if air passes into the crankcase side, but it should not leak into the relief side (air cleaner side).
- When air is applied from check side, the valve is normal if passage of air is restricted. When air is applied from the relief side (air cleaner side), the valve is normal if air passes into the fuel tank side but it should not leak into the check side (crankcase side).
Courtesy of GENERAL MOTORS COMPANY