3 beep engine alarm

Where do I start? I discovered last season that my voltage regulator had burnt out and this was causing by battery problems and not the kids playing on the boat leaving lights on.
Now other than the battery going flat I had no other problems with the engine.
Since I replaced the voltage regulator, impeller, engine oil and gear oil I've had this 3 beep alarm every 4 minutes while the engine is in gear. No alarm with the engine running in neutral. Also the engine runs fine while the alarm sounds, no limp mode and not running rough. I've check oil levels and impeller with no issues.
And ideas what it could be?

Type and model might help with getting replys

Thanks.
Had intended putting that info in. Don't know how I forgot.

Mercury 60hp efi outboard. Year 2006.

I would be scratching my head... I'd be calling in the local OB mechanic.
On a search I see an interesting discussion on here: http://continuouswave.com/ubb/Forum4/HTML/003832.html

It seems to point to voltage reg or oil pressure....

Thanks for that JimC. I've read a lot of similar info on this. I'm not sure what to make of it all. I remember a long beep from the engine to which I stopped immediately. I had a look around the engine, made a few checks and started her up again. There were no issues again. The engine ran fine, no limp mode or anything strange. I ran for at least one season with a burnt out regulator with no warning beeps. They only started after the regulator was replaced. Which is actually working now. I think I'll just have to get a diagnostic machine check done on it.

That would make sense. It my be a faulty sensor.

hi andrew i have the manual and here is what it says about the alarm going of 3 beeeps every 4 mins failure detected with the battery voltage ECT open detected at key up / short detected with engine running / fuel injector detected while cranking/running if it was ok before you replaced the voltage regulator then i would be checking this first to make sure the wiring is ok

Thanks seacloud. I would have expected those beeps when the regulator failed, but they never happened which made me wonder if they are coming from a memory.
I hope to take the boat for a spin on Thursday to see if I've solved the problem. I'll check the wiring again first. I've gone over all the work I've done on the engine and double checked it.

The regulators on merc's are delicate enough. Connecting the battery the wrong way can be enough to blow them or a bad battery connection can do it as well. The warning beep could be cause by cavitation, if its happen only when the engine is running. If its happening at high revs, then try trottling back and see if it continues. An intermittent beep could be caused by a problem with oil...

Thanks for all the replies. I had the boat out over the weekend and once again the alarm was back. I know the oil level is right and the gear oil is full and the impeller is working fine. Which leads me to the voltage regulator, while it is charging the battery it does reach over 17 volts. I am thinking this may be causing the alarm. I am going to reinstall the old regulator just to see if the alarm stops.

sounds like ur volt reg alrite mate , 17volts is way too high

That's what I was thinking.

Finally got my problem fixed. It turns out that the regulator I fitted was faulty. I have since replaced it with another one and the alarm has stopped.