1997 Johnson Evinrude "EU" 90, 105RW, 115, 150, 150W, 175 60 LV Service Manual, P/N 507268, Page 99Get this manual
Recirculation System Servicing
Important disfunctional recirculation system will cause one or more of the following operational symptoms:
Erratic or poor idle characteristics Fouled spark plugs in lower cylinders Excessive smoke when accelerated after extended idle Idle quality unusually sensitive to trim angle
Before proceeding with these tests, the engine's operating temperature must be above the minimum specifications listed in Section 41Start the engine and operate at idle speed
2Remove the aft end of No.1 cylinder recirculation hose from fitting on the cylinder blockSubmerge end of hose in cup of water: If bubbles appear, proceed to Step If no bubbles appear, proceed to Step 4
INote Check all recirculation hoses before proceeding
3Stop the engineRemove the carburetors and intake manifold assemblyCheck the cylinder block fitting and cylinder check valve by injecting isopropyl alcohol into the fitting with syringe: If valve allows flow only from the manifold mounting surface toward block fitting, valve is OK If valve allows flow in the opposite direction, in both directions, or resists flow in both directions, replace valveRepeat this test for each cylinder42717