Have a mercury 90elpto on a 16'' Whaler getting a solid tone and throttle back on take off about half the time pull the throttle back and the tone goes away and throttle up goes with no problem. Oil tank is full and recently replaced the water pump. Any suggestions?
Make (of engine): Mercury
Model (of engine): 90elpto
water pump and oil fill
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Solid tone would be the over temp or low oil alarm. Your description of how it will go away by throttling back only reinforces that thought.
How long ago did you replace the impeller? Are you getting a good stream from the tell-tale?
Do you have the auxiliary tank in the boat? or just the one mounted to the side of the motor?
Replaced the impeller about 6 weeks ago great stream of water out the pee hole. Oil tank is mounted on the engine in front and is very large and full of oil. Seems to me if it was overheat the tone would not go away immediately after pulling the trottle back.
Aha, you didn't mention that it went away immediately.
OK, You are going to have to test this in the water, but disconnect the low oil switch and test the boat. If the alarm fails to come on with the alarm disconnected, your switch in the oil tank is to blame.
12 years Certified marine mechanic, performance boat builder