voltmeter has high speed fluctuation

[paul c 2]

I have an 88 OMC 3L and I noticed today that the voltmeter has a high speed fluctuation (on the needle that is, not at high speed in the boat). It fluctuates fast ebough to be a blur with a low point at about 11 volts (hard to tell exactly)and a high point at around 13. Every so often all the electrical gauges will twitch in unison like the battery power is interrupted. I'm sure the blurring gauge is telling me there's a problem like it's sensing AC from the alternator rather than DC indicating a diode problem? Has anyone seen this before and what the heck causes it ?? The twitch must be an intermittent somewhere in the ignition circuit??

 

[SlowlySinking]

Re: voltmeter has high speed fluctuation

paul c 2, it sounds like a diode problem, assuming your alternator has a plug in field/sense connector, disconnect it and start the engine, if the needle fluctation goes away you found the problem; the alternator. No matter what you find and to save a lot of bux I would remove it and have it tested before you buy another.

 

[Mikedg]

Re: voltmeter has high speed fluctuation

If all the gauges are twitching, I would check for a bad ground or a bad positive feed to the gauges if the alternator tests OK.

 

[pconsolini]

Re: voltmeter has high speed fluctuation

I'll pull it out tonight and haul it over to Advance to see what's what. Hopefully, the'll have the diode set if that's the problem. I presume most of the innards are the same as an auto alternator except for the spark arrestor screens.