Bought a 2016 pontoon last fall ran great all summer,last time before taking it out for winter storage the temp alarm went off shifted it to neutral then reverse then back to forward ran fine for a little bit then alarm went off again. Boat out off the water now. Any advise for next spring? 150 ho on a 22 foot pontoon checked and cleaned intake boat stays in the water all summer.
Whenever there is an overheat condition, the water pump and the thermostats are the first things that should get attention, inspection, and possible replacement.
Your motor also has a water-cooled onboard computer called an EMM that could be getting too hot. You will need a dealer tech with the diagnostic software to check your motor to find out exactly where the overheating occurred and to suggest a course of action.
"There is never just one thing wrong with a boat";
-- Travis McGee, main character in a book series by John D. McDonald
The factory recommends that a properly trained technician service your Johnson or Evinrude outboard motor. Should you elect to perform repairs yourself, use caution, common sense, and observe safety procedures in the vicinity of flammable liquids, around moving parts, near high-temperature components, and working with electrical or ignition systems.
The information offered here is only general in nature and should not be construed as complete factory approved procedures, techniques, or specifications. Always use the proper service manual for your motor, up-to-date service literature, the correct tools, and have an understanding of how to proceed with troubleshooting and repair methods. If you are unsure or uncomfortable with a procedure, a situation, or a technique, enlist the services of a factory trained technician.