1990 Johnson Evinrude "ES" 9.9 thru 30 Service Manual, P/N 507871, Page 118Get this manual
Functional TestsS.L.OWTM The 20 thru 30 HP ignition system incorporates the SLOW.TM warning system which will limit engine speed to approximately 2000 RPM when engine temperature exceeds 1800 (82 C)To resume normal operation after the SLOWTM warning system has been activated, the engine must cool to 1550 (68 C) and the engine must be slowed to an idleThe S.L.O.W TM warning system depends on input from the temperature switch tan leadOn remote electric start models, the SLOW TM warning system is isolated from other warning horn signals by blocking diode in the engine wiring harnessTemperature Switch 1Disconnect temperature switch tan lead2Install correct test propellerStart engine in test tank and run at 3500 RPM 3Attach engine harness tan lead to clean engine ground If engine slows to approximately 2000 RPM, test temperature switchRefer to Temperature Switch Test, Section