1991 evinrude 150 intruder ovrtheat alarm.

[C. Wood]

Starts fine, runs fine for 10 min then the alarm sounds. Still idles ok but when you throttle up it sputters up and down. If I let it sit off for five min. it starts and runs fine as long as I take off before alarm starts. Alarm does not go off if I plane off but as soon as I idle for 5 or 10 min. it starts again. If its an overheat alarm would that make it run as described and then run fine when it cools down? Or is it a vacuum alarm?

 

[Bosunsmate]

Re: 1991 evinrude 150 intruder ovrtheat alarm.

Put your hand on it and see if its very hot. You should be able to put your hand there for a couple of seconds.
Have you changed your thermostat/poppet/ impellor lately?

 

[pn]

Re: 1991 evinrude 150 intruder ovrtheat alarm.

assuming your peeing, as bosun mentioned i'd check/clean thermostats for the overheat issue, look up the manual for location(top of heads)

check fuel system gas/lines/carbs for sputter issue because a hot motor i believe should take off too

 

[emdsapmgr]

Re: 1991 evinrude 150 intruder ovrtheat alarm.

You did not mention anything about the telltale. Either a bad impeller or the thermostats are stuck shut (or both.) Will cause a horn at idle. Once you get the boat up on plane, the increased water pressure causes both stats to retract in their housing-providing increased water flow through the powerhead and significantly more cooling-silencing the horn. Once you slow to idle, you must have a good impeller and two functioning stats-or the horn will start to sound again. A strong telltale may indicate the impeller is functioning normally. If so, you probably need to replace both stats.