i have a 88 merc black max 150 xr4. the temp alarm was on nonstop. the motor started running like crap and after process of elimination, it came down to the switch box's. replaced those and it runs great now. however the darn steady beep comes on but only at wot. before when it was on all the time, wasn't too worried about it. but since i replaced the switch box's and it is only coming on at wot, i am worried. replaced water pump, impeller and it pees strong. thermostats are brand new. i read poppet is for mid range rpm. any help is appreciated.
