1992 Johnson Evinrude "EN" 40 thru 55 Service Manual, P/N 508143, Page 335Get this manual
Motor TestNo Load Securely fasten motor in suitable fixture before proceedote.mg Wit hIS test1Use battery rated at 360 cold cranking amps or higher that is in good condition and fully charged to perform this test2Connect 0-25 amp ammeter in series with the battery's terminal, ammeter Red lead toward terminalDR4238
3Attach or hold vibration or mechanical tachometer to the motor while performing this test4Monitor motor RPM and current drawRefer to the chart below for the correct specifications for your motor