CONTINUOUSWAVE

On a 1998 Mercury 200-HP OffShore with around 300 hours, I know multiple beeps indicate either oil alarm or [over] heat alarm. But here's what I need help with: before, when I would turn the key on, it gave me a series of beeps to let me know the alarm system is working. After a few beeps, it goes off. Now, when I turn the key on, the beeps continue and won't go off whether the engine is cranked or not. If I crank it, beeps continue (as fast as they can beep). If I just turn the key on without cranking engine, it beeps as fast as it can and won't stop until I turn it back to off position. Any ideas of where to start? Thanks.

In any alarm system, when an alarm occurs there are four possibilities:

--there is an alarm condition, a sensor has detected this fault, the alarm system is working properly, and the alarm sounder is working properly; there is a valid alarm;

--there is no alarm condition, a sensor has malfunctioned and is falsely signaling an alarm; the alarm system and sounder are working properly, but this is an invalid alarm; or

--there is no alarm condition, all sensors are working properly, but the alarm system has malfunctioned and is signaling a false alarm condition; the sounder is working properly, but this is an invalid alarm; or

--there is no alarm condition; all sensors are working properly, the alarm system is working properly, but the alarm sounder has malfunctioned and is sounding a false alarm.

From your narrative you describe an alarm condition that is signaled before the engine is started. Check the alarm system--sorry but I don't know the details of your particular Mercury engine--to see what possible sensors could indicate an alarm before the engine even started. For example, if there is a low-oil-reservoir-level sensor, maybe this condition is signaled immediately upon application of electrical power to the engine.

Usually the cadence of the alarm sounder in interpreted to identify which sensor is operating the alarm. Check the alarm system--sorry but I don't know the details of your particular Mercury engine--to see which sensors signal with what cadence. Usually an over-heat sensor is a steady BEEEEEEEEEEEP. A BEEP BEEP BEEP usually comes from something other than overheat.

To test the system, disconnect the sensors one at a time. See if you can identify the sensor causing the alarm. If no sensor seems to be signaling an alarm, then move to the alarm module itself. I think you can find many prior discussions about alarm problems with Mercury outboard engines in the archives of the old forum in which the alarm module was the cause of false alarms. I don't now of a procedure to test the alarm module, other than to disconnect the sensors from it.

Finally, it is possible that the sounder itself has failed and is causing this alarm.

Here are a few prior discussions. Your inquiry is not the first on the topic of BEEP BEEP BEEP from a Mercury outboard:

https://www.google.com/webhp?sourceid=c ... EP+Mercury

If the alarm is associated with the oil-gasoline fuel mixing system, you should read

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

The above will give advice on alarms and testing.

I'm familiar [with] Mercury engines. [The cause of the aural alarm going BEEP BEEP BEEP made be] possibly the oil reservoir float switch. I had the same [aural alarm going BEEP BEEP BEEP] a few years ago, and I replaced the [oil reservoir float] switch. What's the serial number of your 200?

If the cause of the continual BEEP BEEP BEEL aural alert from the Mercury engine is a fault with the oil reservoir float switch, then test this theory by disconnecting the circuit from the oil reservoir float switch. See if the circuit oil reservoir float switch is giving an open-to-ground or a closed-to-ground connection. Then try the opposite for the conductor to the alarm module.

OUTRAGESTEVE: how is the oil reservoir float switch wired? Is it OPEN when the level is TOO LOW? Or is it CLOSED when the level is TOO LOW? Is the switch a circuit to ground? Or is the switch a floating circuit? Share some of your familiarity with Mercury to help us understand how this oil reservoir float switch works.

Also, I recall that some models have a magnetically operated switch and the FLOAT in the oil reservoir becomes saturated with oil, loses its buoyancy, and no longer floats. The actual SWITCH is fine, but the the magnet and float that operate it are just no longer floating. There is no point in replacing a perfectly good switch only to find out the float is the real cause of the problem.