2004 SR Johnson 2-stroke 40, 50HP Service Manual, Page 154Get this manual
FUEL SYSTEM OMS PUMP Place new washer on air motor diaphragm screwHold air motor diaphragm under intermediate housing with poppet valve pushed upScrew head is held in hexagonal recess only when poppet valve is pushed upPush fuel piston down and spin air motor diaphragm on to stem13Washer Poppet valve
2Air motor diaphragm
Position air motor diaphragm with screw next to stem (The fuel diaphragm can be pushed down to extend stem through intermediate housing for better visibility Hold air motor diaphragm screw up against stem and turn fuel diaphragm few revolutions to start screw in stem threads