posted 04-09-2006 01:10 PM ET (US)        

I got on plane and it stopped.

We stopped, fished, and it did the same thing. Once again I got on plane, and it stopped.

I checked oil level; it was more than sufficient. The temperature of the motor was well within range.

We started working our way back [toward the dock] out of concern [about the motor and its alarm], but we stopped one more place. Got into the fish some good and stayed there for two hours, which I didn't mind so I could see if [the alarm was being caused by a] a temperature [problem].

I started motor and the alarm came on instantly. I got on plane and [the alarm] didn't shut off. I took it easy and we ran into the dock.

I have now gotten [the boat and motor] home, added oil in the reservoir just as a precaution. and run the motor in a fresh water tank. Once again, the second I started it, an alarm came on and stayed on.

posted 04-09-2006 05:23 PM ET (US)            

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. You also neglect to mention the model and horsepower.

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/reference/mercuryOilInjection.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.

I'll be glad to help you work through the maze of possible causes for this alarm. But first tell me two things:

--what horsepower and model is your motor?

--does the alarm beep the proper cadence when you turn the key from OFF to ON?

posted 04-12-2006 01:33 PM ET (US)            

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