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1994 Mercury 115 OB

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wolfpch

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The alarm is sounding on my 19

The alarm is sounding on my 1994 115 and it is the one attached to the ignition harness. It started when I was towing a tube and now it stays on constantly. If I start my boat the next day it come on right away. I disconnected the two blue wire from oil res and it still sounds. I have blue smoke and water is coming out of top hole so pump is working. any help?
 
"That's an overheat alarm

"That's an overheat alarm - so either your sensor is shot, you have short in the wiring somewhere, the alarm itself is busted, or it's really overheating."
 
water is coming out of top hol

water is coming out of top hole and is not hot. If I start the boat right now the alarm will sound constantly. Any thoughts and that is after the engine has sat a couple of days.
 
"If you look near the top of t

"If you look near the top of the head, just below the thermostat and poppet cover you should see a black wire coming out.

That is the temp sensor. Follow the black wire down to a little terminal block (a little two post thingy that will have a few wires going to it - another black, a tan, a blue/tan etc).

Undo the post and remove that black wire that is feeding from the temp sensor.

If that cures your problem, then the sensor is shot (quite a common issue). If the horn continues then you know it's the alarm module itself that is shot."
 
I could not find what you are

I could not find what you are referring to. About even with top spark plug to the starboard side is a brass plug Temp Senor? with a tan wire coming out. I disconnected and alarm still sounded but I am not sure if I was in the right area. The back of the motor where spark plugs are is what I was working with.
 
"Sorry, steered you wrong ther

"Sorry, steered you wrong there. That is the temp sensor for a gauge, not the overheat sensor.

Try this. From (looking at the prop end), look on the right side of the powerhead. You should find a sqare box on the side kinda in the open (easy to see). It has two blue wires, a tan, a black and a purple wire going to it.

Follow the black or the tan wire back to a little two post terminal.

At the little terminal, one of the posts should have the tan that you followed, a tan wire with a blue stripe and a black wire all ganged together. If you remove the black wire there (and just reconnect the tan and tan/blue) you will have disconnected the overheat sensor..."
 
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