Mercury 90-HP Aural Alert Sounds

Repair or modification of Boston Whaler boats, their engines, trailers, and gear
roguewave
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Mercury 90-HP Aural Alert Sounds

Postby roguewave » Thu Aug 17, 2017 4:35 pm

[On A Mercury 90-HP outboard engine on a 1998 MONTAUK 17] I hear a buzzer sounding. A few days prior to hearing the buzzer sounding, I filled both the [fuel] and oil [tanks].

I found the source of the [buzzing sound] under the console, see picture. [The buzzing occurs] when I turn the key on, and when the engine is running. It seems to actually get louder with more engine speed.
Help!

Image
..."some gave all, KIA"...

roguewave
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Re: 1998 17 Montauk, 90HP merc. Siren going off???

Postby roguewave » Thu Aug 17, 2017 5:12 pm

I got close up inside and saw the name on it "Floyd Bell Inc"
..."some gave all, KIA"...

roguewave
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Re: 1998 17 Montauk, 90HP merc. Siren going off

Postby roguewave » Sat Aug 19, 2017 5:25 am

I'm guessing there is a bad oil or overheat sensor. It's a 2 stroke,
..."some gave all, KIA"...

jimh
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Re: Mercury 90-HP Aural Alert Sounds

Postby jimh » Sat Aug 19, 2017 8:41 am

Locate the owner's manual for the Mercury 90-HP outboard engine. Read the owner's manual section that explains the meaning of the aural alert sounds. Generally, on these older outboard engines using designs from the 1970's, the sounding of an aural alert is only indicative of the existence of a problem. In order to interpret the meaning of the aural alert, the operator must assess the cadence of the aural alert sound and the situations when the aural alert occurs in order to make a reasonable inference about the meaning of the aural alert and exactly what sort of problem it is trying to notify has occurred.

In any alarm or warning system, there are two possible causes for an alarm:

--the warning system is working properly, and the aural alert is sounded to alert you to a real problem;

--the warning system is working improperly, there is a false alarm, and the aural alert sounding is not indicative of a real problem; the problem can be in any component of the system, including sensors, the central processor, or the aural alert sounder itself.

With these older Mercury engines, sounding of an aural alert is often due to one or more failures of system components, sensors, or the alarm itself.

To investigate further, obtain the service manual for your Mercury outboard engine. The service manual will explain in further detail how the aural alert warning system works, what sensors are involved, and what exactly controls the aural alert sounder.

Failure of the aural alert warning system on Mercury outboard engines is a common fault.

Read the 70 prior discussions about these problems with this search:

https://www.google.com/search?hl=en&sou ... gle+Search

If your Mercury outboard engine has an oil-gasoline mixing system similar to the one described in a c.1998 manual, see a reproduction of a section of the service manual that will explain how the oil system works and what sensors are involved in monitoring its operation in the REFERENCE section article I published many years ago:

http://continuouswave.com/whaler/refere ... ction.html

jimh
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Re: Mercury 90-HP Aural Alert Sounds

Postby jimh » Sat Aug 19, 2017 8:47 am

The increase in the loudness of the buzzing sound in correlation with an increase in engine speed can be interpreted to be caused by an increase in the 12-Volt battery voltage due to increased charging current output from the engine when the engine speed increases. I would not delve too deeply into this relationship as being some sort of diagnostic clue in your investigation into the cause of the aural alert. That the aural alert sounds before the engine is started seems to rule out any possible correlation with engine speed.

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Re: Mercury 90-HP Aural Alert Sounds

Postby jimh » Sat Aug 19, 2017 8:49 am

A close visual inspection of the aural alert and identification of some sort of branding or manufacturer is unlikely to lead to further insight into the cause of the aural alert being sounded.

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Re: Mercury 90-HP Aural Alert Sounds

Postby jimh » Sat Aug 19, 2017 8:56 am

If you read the first article in the search results I directed you to (above) you will find my advice given earlier to a fellow in a similar situation. I recommended as follows:

My first recommendation is that you immediately switch over to a fuel using pre-mixed oil and gasoline at a ratio of 1:50 until you solve this problem. This will save you from destroying your motor by running it without oil while looking for the cause of the alarm.
The owner's manual of almost every outboard will contain information about how to interpret alarm signals. I do not have the owner's manual for your outboard.

In general I have found that the literature published by Mercury about their outboard motors is quite good, and it will explain in detail how your motor works and how to interpret any alarm conditions it gives you.

If your Mercury outboard has an alarm system which is similar to the one described for a c.1989 motor, you can read about it in the Reference section. See:

http://continuouswave.com/whaler/refere ... ction.html

For the moment, we proceed on that assumption.

The alarm module is somewhat limited in its ability to pass information to the owner. It only has an aural signal. It modulates the cadence of the aural signal to indicate the function. There are only three possible cadences.

When the key is turned from OFF to ON, the alarm sounds a signal to verify that it is operating properly. This signal sounds like a Morse code letter D or B, i.e., "dah-didit" or "dah-dididit". If the module does not sound this signal it is malfunctioning.

After engine start, the alarm goes silent until there is an alarm condition.

If the engine temperature rises above the threshold of the thermal switch in the cylinder head, the switch closes. This causes a continuous tone alarm which persists until the temperature falls enough for the switch to open. This ends the alarm tone.

Any of the following conditions will signal a BEEP-BEEP-BEEP:

--oil level below the float switch level in the under-cowling reservoir

--input gear shaft to mixing pump turning too slow in relation to engine speed

There is no way to tell which of these events causes an alarm. You have to deduce which is the problem by inspecting the motor.

It is also possible that any of the following conditions will also signal a BEEP-BEEP-BEEP:

--defective float switch in the under cowling reservoir

--defective motion sensor in the mixing pump

--defective ignition module sending false signal

--defective alarm module creating false signal

If you want to diagnose this problem further, you will need to obtain the service manual for you engine. Thoroughly read the service manual. It will cover the oiling system and alarm system in detail. There are many complex interactions which can cause these alarms.

For example, there are seven different situations which can cause the level in the engine reservoir tank to be low.

Problems with these Mercury alarm modules seem to be very common.

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Re: Mercury 90-HP Aural Alert Sounds

Postby jimh » Sat Aug 19, 2017 11:10 am

roguewave wrote:...Help!


I hope my remarks here in this thread and the 70 other articles on similar aural alert problems will be helpful. Please let me know if they were.

Paul A
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Re: Mercury 90-HP Aural Alert Sounds

Postby Paul A » Sun Aug 20, 2017 8:19 am

Jim,

Your input is ALWAYS helpful. I just went through all of this. Using your reference material I could direct and "coach" the mechanic and save some time/money! Problem solved. Can't expect a mechanic to be so logical, except a good one.

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Re: Mercury 90-HP Aural Alert Sounds

Postby jimh » Sun Aug 20, 2017 8:40 am

PAUL--what was the remedy? I'd love to know. The more information we can share about these aural alert problems the better the diagnostic ability to find the cause.

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Re: Mercury 90-HP Aural Alert Sounds

Postby roguewave » Sun Aug 20, 2017 9:27 am

Thank you Jim for the weath of info, I'm workin' on it.
..."some gave all, KIA"...

roguewave
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Re: Mercury 90-HP Aural Alert Sounds

Postby roguewave » Sun Aug 20, 2017 8:53 pm

I think I unplugged the "overheat" sensor wire coming off the head: nothing changed.

I then unplugged one of the two wires coming from the bottom of the oil reservoir which I assume is an oil level sensor: the noise stopped.
..."some gave all, KIA"...

jimh
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Re: Mercury 90-HP Aural Alert Sounds

Postby jimh » Sun Aug 20, 2017 11:48 pm

I forgot to point you to another article I wrote (just recently) on this topic. See

Mercury Warning BEEP-BEEP-BEEP or BEEEEEEEEEP
viewtopic.php?f=6&t=2139

This will help you with the electrical circuitry--if it applies to your engine.

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Re: Mercury 90-HP Aural Alert Sounds

Postby jimh » Mon Aug 21, 2017 12:07 am

roguewave wrote:I think I unplugged the "overheat" sensor wire coming off the head: nothing changed.

I then unplugged one of the two wires coming from the bottom of the oil reservoir which I assume is an oil level sensor: the noise stopped.


See my most recent reply.

I would suspect the alarm module itself. Low oil is supposed to produce a BEEP-BEEP-BEEP alert. Try the diagnostic procedure I describe in the most recent article I linked you to above.

Paul A
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Re: Mercury 90-HP Aural Alert Sounds

Postby Paul A » Mon Aug 21, 2017 9:31 am

MY 1992 MARINER 75 HP had a continuous BEEEEEEEEEP that was an oil sensor problem even though the common belief is that a continuous BEEEEEEEEP is identifying a temp problem. It was definitely a sensor and not the alarm itself. Motor was still smoking normally during the very short run time during alarm so no engine damage. Serviced expertly by Twin Cities Marine, a Whaler dealer, in Two Rivers, WI. (great source for Whaler parts by Sue).

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Re: Mercury 90-HP Aural Alert Sounds

Postby jimh » Mon Aug 21, 2017 10:36 am

PAUL--what component of the alarm system was replaced to provide a remedy?

Paul A
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Re: Mercury 90-HP Aural Alert Sounds

Postby Paul A » Mon Aug 21, 2017 2:50 pm

Invoice stated "Replaced oil warning module which was the cause of the alarm" and replaced "low oil sensor because the wires were corroded and gone". You could call Twin Cities Marine (Kris) for more detail - Paul's restored 1966 Nauset. Temperature sensor was tested and worked properly.

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Re: Mercury 90-HP Aural Alert Sounds

Postby jimh » Mon Aug 21, 2017 4:55 pm

PAUL--so the alarm module was replaced due to malfunction. That would have been my diagnosis. And the float switch in the oil tank was replaced due to decay of its wiring. Often the float switch goes haywire when its float loses its buoyancy and no longer floats.

The proper aural signal for low oil is BEEP-BEEP-BEEP, not a continuous BEEEEEEEEP. A continuous BEEEEEEP in a normally working system is a high-temperature alarm. A continuous BEEEEEEP when you have a stone-cold engine is probably a failed alarm module.

Paul A
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Re: Mercury 90-HP Aural Alert Sounds

Postby Paul A » Mon Aug 21, 2017 8:21 pm

Thank you for your concise communication of your knowledge. I'm restoring my second [Boston Whaler boat] this summer, a SPORT that was made in 1975, taken out of service due to hull damage in 1977 and kept in a garage for 30 years--and best yet $500. I'm doing a complete restoration with the best materials and process learned from this site. I finished the 1966 Nauset that I had in my garage for 25 years. I regret turning down a firm $8,200 offer for that one yesterday--because of the cost of perfection. I may just make this more than a hobby.

roguewave
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Re: Mercury 90-HP Aural Alert Sounds

Postby roguewave » Wed Aug 23, 2017 1:10 pm

Can't thank you enough Jim!
..."some gave all, KIA"...