tachometer and voltmeter start to max out after approx 2500rpm

The problem I have,

I have a 1997 Maxum with 3.0 mercruiser
The boat starts fine and works fine until approx 2000 rpm. After adding more power the voltmeter starts to jump from left to right violently, then if add more power the voltmeter will max out at more than 16(max reading on my voltmeter) volts and lay on the side, if add even more power the engine will stop working properly, some electrical clicking sound will start from under the engine cover and the rpm will max out at more than 7000 rpm (engine is not even running at that rpm).
So far I have removed alternator with the regulator and will have them checked out and rebuild/replaced if necessary.
I am worried about the electrical clicking sound at the back, could it be high voltage coil as well or other electrical compenents(I mean alternator and regulator are actually fine)? Or which electrical components are common to trigger regulator to make it think the alternator needs to produce more power?
Some other indication of higher voltage I had was 1. fishfinder got switched off by itself(it will do it automatically if more than 18 volts) and 2. the fuse got blown on the radio.
At this time I was towing a tube and everything seemed fine until engine started to choke and then I noticed voltmeter maxed out rpm maxed out past 7000 then i stopped. Then after stopping the fishfider was off and radio fuse was blown. I was able to get back slowly under 2000 rpm, everything works fine under 2000 rpm, volmeter will show 13.5 volts the fishfineder will remain on and the engine works smoothly, if adding more power those problems start. If anyone had similar issues please share.

Thanks

Re: tachometer and voltmeter start to max out after approx 2500rpm

I just got a word from an electrical shop what my alternator and regulator function fine and nothing needs to be rebuild. So far I got new battery and also bought new alternator just in case and will keep my old one as a back up and tried the boat. The problem is still there. Will be checking the electrical components now, like spark plugs, cables, rotor, etc.
Hope to find and and fix the problem asap to get ready for waterskiing this weekend.
Any help or suggestion is greatly appreciated.

Re: tachometer and voltmeter start to max out after approx 2500rpm

This is interesting. what does the voltmeter on the fishfinder say over 2500 RPM?

Have you used a meter to check voltage at those RPM's. I know the guys said they was fine, but I would still be suspicious of the alternator, but possibly mechanical.


To help isolate the clicking, use a chunk of hose, see if you can isolate it.

Re: tachometer and voltmeter start to max out after approx 2500rpm

My fishfinder doesn't show volts, it will just turn off by itself as a precautinary if voltage will be more than 18 volts, i found this in the specs for this type of fishfinder.
Anyhow, after replacing alternator, disconnecting all fat black and red cables cleaning the connections and tightening all the wires back tightly, I went out in the water again to try it out.

At first everyting seemed normal, voltage would stay at 14 and the engine would operate smootly, After about 10 minutes i started to hear the electrical clicking sound from the engine cover and boat would experience backfiring for 2-3-5 times, the tachometer would be searching (moving slightly forward and back) and then return to reflect the actual rpm, the voltage would be maxing out as well, this would continue for a minute or so then would be back to normal. Another thing I noticed, if I would put some electrical load on the system, like engage hydraulic pump, to adjust the lower end pitch, the voltage will immediately jump to above 16 (max setting on my gauge)
and then the electical clicking and backfiring for a minute then back to normal: voltage 14, engine working smoothly.
What could be the cause?