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Old 07-25-2018, 05:12 PM   #1
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Tach problem

I have an wavering tachfor the Starboard engine.

The boat has twins diesels with dual stations.

Both upper and lower station Starboard tachs. jump around although above 1,900 RPM they are fine.
The port tach is o/k.
The Starboard tach was rebuilt with a new pickup installed at the time.

I have switched the feed to the Starboard tach to the port tach and the problem follows the feed from the alternator.

Some time ago i changed the regulator for the starboard alternator--no change.

I have started cleaning some of the connections but no fix so far.

Anyone with this issue ?

Thanks,
Bill
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Old 07-25-2018, 05:44 PM   #2
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Start at the beginning. How does your tach get its signal from the engine. Is it getting it from the alternator or is there a mechanical pickup.
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Old 07-26-2018, 07:22 AM   #3
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If your batts are paralleled, one alternator will go to sleep and the other will do the charging. Then no signal to the tach. Can be as simple as opening a batt cross tie switch.
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Old 07-26-2018, 09:47 AM   #4
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Quote:
Originally Posted by Ski in NC View Post
If your batts are paralleled, one alternator will go to sleep and the other will do the charging. Then no signal to the tach. Can be as simple as opening a batt cross tie switch.
Yup. Mine will do this as well. Just need to get a little load on both alternators.

Ken
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Old 07-26-2018, 11:33 AM   #5
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Just went through this exercise. Make sure every crimp is tight at the alternator and the gauges. Particularly the alternator as if any are loose the engine vibration will make and break the circuit. All of the other suggestions are great to check as well. Also, make sure every connection at the back of the instrument panel are tight, too.
It can drive you nuts, but keep searching.
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Old 07-27-2018, 06:16 AM   #6
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Thanks for the suggestions,
I'll keep plugging away.
Bill R.
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