93 115HP Mercury 2 Stroke - Alarm beeping on and off and won't stop

convergent

Petty Officer 1st Class
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May 17, 2010
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Out with the kids water skiing today for several hours and while I was pulling my daughter, the alarm started going off. It was not continuously on, but beep and off, beep and off, about once a second and just keeps doing it. Does anyone know what that signal means. I shut it off and used the trolling motor to get back to dock. Tried to start it again and it kept doing it. What should I look at in diagnosing it?
 

sxmerc

Petty Officer 1st Class
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Jul 13, 2010
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Re: 93 115HP Mercury 2 Stroke - Alarm beeping on and off and won't stop

Ready? Here's the stupid question... Is there sufficient oil in the oil tank?
 

convergent

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Re: 93 115HP Mercury 2 Stroke - Alarm beeping on and off and won't stop

Yep, I filled the tank before we went out and I think we were out from about 2pm til 7pm... so no way it would use a tank that quick. So this is an oil warning I'm taking it? Just looking through the service manual on how to test the sensor. The oil pump was just replaced by the prior owner in April of this year... I talked to his mechanic, so I'd be surprised if the pump is bad. Am I right that this is the low oil warning signal?
 

73Trihull

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Oct 31, 2009
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Re: 93 115HP Mercury 2 Stroke - Alarm beeping on and off and won't stop

Could be engine temp. Sometimes if weeds get around the water intake the alarm will go off because of a lack of cooling water.
 

convergent

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Re: 93 115HP Mercury 2 Stroke - Alarm beeping on and off and won't stop

OK, I'm a little confused by the service manual, but it seems like I have a bad sensor. According to the manual, the sensor test is done by pulling the black and brown wires from the terminal block and checking for continuity. I did that test and it passed... no continuity which should indicate the oil tank is full. So far so good. But further in the manual in the troubleshooting section it tells you to test the sensor by pulling the two blue wire connectors and testing for continuity. I tested there and its showing shorted... so that says the sensor is bad. The first test is actually going through the module... the second test is going straight to the sensor. So base on this, I think I have a bad sensor, correct?

Assuming that is correct, it looks like the sensor is just attached to the bottom of the tank with one philips screw. I'm assuming when I remove it, all the oil is going to come out, right? So do I need to remove the tank, or just pull the line and empty it?

One more question. If I disconnect the sensor, then the ignition self test works.. one short burst then no alarm. If I connect the sensor, it goes off on the self test... again pointing to a bad sensor. Is this sensor ONLY FOR LOW OIL IN THE TANK? So, if I know the tank is full, can I disconnect the sensor to continue using the boat until I get a replacement? Is there something else checking to make sure the oil pump is functioning? I don't want to fry my motor if I get a second problem... like the oil pump stops working... and I know I won't run the oil tank out of oil because it never drops more than half way even after a whole day of boating?

Thanks for the help.
 

convergent

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Re: 93 115HP Mercury 2 Stroke - Alarm beeping on and off and won't stop

OK... read a bunch more threads and looks like I can just disconnect the sensor for the time being. If I'm wrong on that, please let me know.

Is it true that I'm going to have to replace the whole oil tank? I'm not finding the sensor on the Mercury parts website and I've seen a few people on here say that you have to replace the tank. The sensor looks like its attached with a philips screw on the bottom of the tank... amazing that this isn't replaceable. So can someone confirm this and whether Mercury is the only source for that part... sensor or tank.

Thanks.
 

sxmerc

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Jul 13, 2010
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247
Re: 93 115HP Mercury 2 Stroke - Alarm beeping on and off and won't stop

The oil tank sensoe IS replaceable part# 87-12886A 6. The oil tank will not drain once you remove the sesor. The sensor actually sits inside a well in the tank, not in the inside of the tank. Remove the sensor from the tank and do your continuity check. There is a POSSIBILITY that the problem is the float on the tank, and not the sensor. Float failures are common on these motors, but not always the problem. Hope this helps.
 
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