1985 OMC 65, 100 and 155 HP Models Commercial Service Manual, PN 507450-D, Page 130Get this manual
Removal of Intake Manifold100 and 155 1155 ModelsRemove primer solenoid screws2155 ModelsDisconnect hoses from primer solenoid 3Remove shoulder screw, wave washer and washer (behind cam), cam and lay cam aside4100 ModelsRemove starter solenoid and electric starter
5155 ModelsRemove fuel pump to intake manifold screws (two each) and lay fuel pump and hoses aside6100 ModelsDisconnect recirculation hose aft of throttle lever on starboard side of engine7Remove screws (55 Models16) (100 Models8) and intake manifold Discard gasket8If necessary, remove screws from front of intake manifold and remove the leaf plate assemblies from the intake manifoldDiscard gasketLeaf plate assemblies are serviced only as an assemblyDo not remove valves and stops
Intake Manifold100 and 155
Inspect recirculation check valve assembliesUsing syringe and 18" I.Dclear plastic tubing, test the recirculation check valves
1I nstall plastic tubing to syringe and fill syringe and tubing with isopropyl alcoholCheck all check valves2Connect end of tubing to check valve Push in slightly on syringe plungerIf no fluid moves, the check valve is closed and workingIf fluid flows in the tubing, check valve is stuck open and must be replaced3Pull out on the syringe plungerAir from the check valve should enter the tubingIf the check valve fails this test, replace itA bad valve will create poor idling engine4Refer to Cleaning, Inspection and Repair