1998 Johnson Evinrude "EC" 90, 115 SPL Service Manual, P/N 520209, Page 85Get this manual
Recirculation System Servicing Function Test
1Connect 1Js inI.Dclear vinyl hose between the recirculation fitting and syringe filled with isopropyl alcoholThe fitting does not have to be removed from the crankcase for this test2Press lightly on the syringe plunger No fluid should move through the fitting
3Draw out on the syringe plunger Air should be drawn through the fitting into the clear hose
4Connect 1Js in I.Dclear vinyl hose between the cylinder block or bypass cover hose fitting and syringe filled with isopropyl alcohol5Press lightly on the syringe Fluid should move freely through the fitting