Honda Outboards BF40A/BF50A Service Manual, Page 291Get this manual
BF40A-BF50A Overheat indicator light (Red) turns ON while the engine is running
NOTE: No problem if the overheat indicator light comes ON when restarting the engine after hot soak at high temperature, but comes OFF after idlin for few minutes YES Remove the foreign material and recheck
1Stop the engine and check the water intake screen for cloggingIs the water intake screen clogged?
2 Start the engine and check the cooling system indicator with the engine idlingDoes cooling water constantly flow through the cooling system indicator?
Check the discharge port for clog ging, clean the discharge port if necessary Check the water pump for wear or damageReplace or repair the water pump Check the water tube for clogging or damageClean or replace the water tube if necessary