25hp Mercury four stroke solid beep

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hsiftac

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Sep 19, 2010
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Location
Peoria Il
Looking for a little help here. I have a 2009 Mercury 25hp elh efi that I have owned since new. Usually do a oil change, lower unit change yearly. Had it serviced last year with new water pump impeller and fluids. I have an ongoing problem with this motor where I will get my boat on plane and it will do the constant beep and limit its revs. I will shut it off at this point and give it a minute. Then I start it back up and no problems whatsoever. I could run it the rest of the day without a problem. I have also noticed if I let it idle for a few minutes before I run it this doesn’t happen as often. Per the manual the steady beep means either oil pressure or overheating. Any tips on how I could figure out which is causing the problem? Could this be a bad sensor/thermostat? I would think if it was truly overheating or having low oil pressure that it would constantly give me this warning vs allowing me to keep running but I am far from knowledgeable when it comes to engines. Maybe someone has experienced this before? I’m just trying to see if there is anything I can do before I spend an arm and a leg at the marine mechanic. Thanks in advance for any advice/comments.
 
What I would do:

If this motor stores a history of faults, let a shop scan it to tell you whether the problem is with pressure or temperature.

IF not, research what type of output signal each sensor uses. Put a meter on one sensor, and then the other, while running the motor in a barrel and try to duplicate the problem. If you own two meters, do both at the same time. This will tell you whether the problem is temp or pressure.

Swap out that sensor and see if the problem goes away. If it does - you saved yourself the cost of a repair. If not, you wasted $ on a sensor but it's still going to be cheaper than shop time.

If the problem continues - you'll have mechanical troubleshooting to do.

Intermittent problems are hard to diagnose - even for the pros.
 
If you think it's the temp sender and the part # you need is 787992, I have a brand new one in the package. I thought mine was bad on my 60/45 jet but it ended up being the module for the oil level/temperature so I disconnected it. I don't think this part is correct for the 25 hp 4 stroke but if it is, give me a shout.
 
Mine said the same thing, water problem, went threw the hole water system, changed water pump , thermostat and cleaned all water channels. Still had a horn solid, checked oil system and found a bad oil sensor, in the day tank. Just drove me mad, every thing I could find out said it was a water flow problem, Guess what, I guess it could be any thing.
 

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