Mercury 35/40HP 2 Cylinder Outboards Service Manual PN 90-42794--1, Page 347Get this manual
Oil Pump Inlet Check Valve Leak Test 1Disconnect both fuel lines (a) from AutoBlend Seal off outlet fitting (b)
IMPORTANT: DO NOT apply more than PSI of air pressure3Apply up to PSI to fuel filter inlet fitting Check valves should not allow drop in meter reading Check rubber valves for cracksholes or debris before replacing both inlet and outlet check va lves if leak occursRefer to disassembly procedures fol lowing