Motor Alarm

[Hillbiehle]

I have a 90hp Mercury. Since last year, a warning alarm stays on as soon as the ignition is turned, even if the engine is cold. I have plenty of oil, imprellor has been changed, and am getting plenty of water discharge. I have also disconnected the battery and the same problem continues. Do you think that it is just a bad sensor or is there something else that I may be overlooking? Any guidance is much appreciated.

[FL SNIPER]

How new is the motor? Is it a 4 stroke? It might be "change oil" indicator that needs to be reset. If you still have your manual, look in there to see how to reset it. I'm sure you'll get a more specific response from someone out there who has a 90HP Mercury...so help is on the way.

[marine_man]

I'd say you've got your bases covered... it almost seems like the float in the oil reservoir is stuck at low, or something along those lines.. or, just a grounded out alarm, especially since it comes on when you turn the key on.

marine_man

[chadly]

Is this motor more than 6 years old. I have a friend who has a 115 merc and the motor is about 7 years old. The oil sensor keeps going out on it.

[Hillbiehle]

Thank you all for the replys and pointing me in the right direction. The motor is a 1990 2 Stroke. I'll post the outcome for anyone else that may possibly experience this problem.

[RobertELee]

check the oil reservoir for sure. My dad has a 30 hp merc w/ oil injection and the alarm would not turn off. Brought it in and they found float sensor had totally broken off from the top of the oil reservoir. Luckily it was covered under warranty.

[Doonbuggy]

I had an '89 Nissan 70hp two stroke and I had the same thing happen last summer. The overheating sensor had gone bad.

Any chance you have been crashing through some big waves recently? Maybe just a coincidence, but the sensor went bad after I spent a couple of days crashing thru some big rollers on LOW.

DB

[Hillbiehle]

I actually towed the boat from the twin cities to Voyegerus Nat'l Park. Although I never had this happen before, as soon as I put the boat in the water the alarm began (not what you want to hear on the beginning of a 4 day fishing trip). Perhaps all the bumps along the way jarred something loose. I'll check the float and sensor. Thanks everyone!

[bullheadslayer]

I had the same problem on my 94 40hp mercury. My problem was the overheat sensor. You may have a different problem but the place to look is to pull the motor cover and look for a square flat box thing on the side of the motor with a screwed cover on it. I dont remember how I found the problem but I do know that it ended up being that box thingy so I went to get a new one, found out it was $150, this was 1996, and just pulled the plug on the whole thing. Been running that way ever since with no problems. Found out later from 3 other mercury owners thats how they fixed theirs also

[marine_man]

I would try and avoid this type of repair...

If your water pump ever completely stops working for whatever reason, or your water intake ports get plugged by weeds, debris, etc you will have no warning and will spend a lot more than $150 to rebuild or replace your engine block.

Are you certain the problem wasn't with the sensor itself?

marine_man

[Willy]

First thing, is it an intermittent beep or a steady one? A steady one is the heat sensor, the intermittent is the oil.

I had the exact same thing happen to my 1991 60 Merc. It was the float inside the oil resivior. I replaced the oil tank and everything was good.

All that oil sensor will sense for you is your oil level. If your oil level is not low, it is probably a stuck float like others have said. The alarm has nothing to do with the injection system, that is why it is sounding as soon as you turn the key on.

If it was the overheat alarm, it wouldn't sound as soon as the key was turned on unless the sensor itself is bad. In that case, a new sensor is needed. Unplug the leads to the sensors until the alarm goes off and you'll be able to tell which one it is that has gone bad if this is the case.

[Hillbiehle]

The beeping is rather annoying intermittent beep about ever two seconds. Did I mention annoying? Anyhow, what great help from each and everyone that has responded. A big thank you to all of you.

[marine_man]

Since it's intermitent it's very likely a oil related problem - very likely a stuck float at the low position.

marine_man

[Hillbiehle]

Well, I installed a new sensor and the thing still beeps. I clipped the wire on the alarm and called it done....

[marine_man]

Well... you've now isolated the problem... if you don't plan on replacing the engine temp sensor be 100% sure you always have an adequate stream of water coming out of the motor...

marine_man