1997 mercruiser 350 magnum tourn ski - no voltage at gauge

[climbabout]

De winterized my 1997 mercruiser 350 magnum tournament ski (carbureted) motor last weekend and all checked out great at home. Took it out last night for the first time this season and it started and ran fine, however I noticed my ammeter gauge was not registering at all. Stopped and checked all electrical connections around the motor and battery and all seemed fine. Boat started right up but still no movement of the ammeter needle. After running for 10min or so, the ammeter briefly registered correctly but then stopped after a minute of so. I also noticed that when I turned my blower or bilge pump on that my readings on my water temp gauge and oil pressure guage changed, so I doubt the ammeter itself is bad, but it must be a failing/failed alternator? What do you guys think? Any troubleshooting advice?

[achris]

Sounds like a ground problem somewhere. Do you have the electrical systems isolated, or are the blower and bilge pump run off the engine systems? If they are, get them isolated.... And check all the grounds. If the Ammeter didn't move, check the battery voltage... with the engine running... It should read around 14Volts, plus or minus.... If not, the alternator could be US...

Chris.......

[climbabout]

Did some thorough investigating this morning -checked all wire connections and all grounds and found nothing unusual- tested the alternator tests per my mercruiser service manual and all voltage tests showed normal readings. Some of the tests requires having the ignition switch in the on position and while the ignition switch was on I could periodically hear a click every minute or two coming from the voltmeter - these clicks were not associated with any action I was performing at the alternator - they were completely random. I even stopped all my tests and just watched the voltmeter gauge for a couple of minutes and it would click at random about every minute or so. At one point the needle registered normally for a few seconds then went back to nothing(which is 8 on my gauge). So I crawled under the dash and checked the voltage at the back of the voltmeter with the ignition on and read 12.5 volts. Turned ignition off - 0 volts, checked again with ignition on and again 12.5 volts. So now I'm thinking, the voltmeter is bad? Everything else seems normal - what do you guys think?
Thanks
Tim
p.s. - my initial title reads "no voltage at gauge" - that it what the gauge read at the lake the other night. I did not have a tester with me at the lake so I was unable to actually read from the back of the voltmeter. So to me it appears the voltmeter is bad, especially considering I my battery is still indicating full charge.

[Bond-o]

Did some thorough investigating this morning -checked all wire connections and all grounds and found nothing unusual- tested the alternator tests per my mercruiser service manual and all voltage tests showed normal readings. Some of the tests requires having the ignition switch in the on position and while the ignition switch was on I could periodically hear a click every minute or two coming from the voltmeter - these clicks were not associated with any action I was performing at the alternator - they were completely random. I even stopped all my tests and just watched the voltmeter gauge for a couple of minutes and it would click at random about every minute or so. At one point the needle registered normally for a few seconds then went back to nothing(which is 8 on my gauge). So I crawled under the dash and checked the voltage at the back of the voltmeter with the ignition on and read 12.5 volts. Turned ignition off - 0 volts, checked again with ignition on and again 12.5 volts. So now I'm thinking, the voltmeter is bad? Everything else seems normal - what do you guys think?
Thanks
Tim
p.s. - my initial title reads "no voltage at gauge" - that it what the gauge read at the lake the other night. I did not have a tester with me at the lake so I was unable to actually read from the back of the voltmeter. So to me it appears the voltmeter is bad, especially considering I my battery is still indicating full charge.

Ayuh,... Yer testin' says the gauge is junk,...

The changes when switchin' on, 'n off the other accessories, says ya got a corroded ground path somewhere...

[Bt Doctur]

With all gauges you need a feed 12V and a ground ,you need both to work.