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Old 06-24-2018, 03:17 PM   #1
City: New Bedford
Country: USA
Join Date: Sep 2015
Posts: 16
05 MS400 - Voltage Gauge


I've got an 05 Trawler with twin Yanmars 240's. Both upper and lower station have the 3 in 1 and 4 in one Faria gauges on the port and starboard sides respectively (fuel, temp, oil, voltage). Everything is good on the lower station. The upper station everything is good except on both port and starboard gauges there is no voltage reading. I haven't thought about the gauges before so I'm hoping for a little primer to get me going on diagnosing the problem. Here's what I think:

1) I highly doubt it's the gauges as all other readouts are functioning (and both are exhibiting same behavior)

2) It's odd to me that both voltage gauges are reading zero ( I could see one side or the other, but both?)

3) It's not the ground or all functions of the multi gauge would not be working

4) Given other things that I've find with the Mainship wiring, it wouldn't surprise me at all if both volt gauges are connected to the same source (which would explain both not working)

5) I assume that there is no sender unit and the gauges read straight voltage (is this correct?)

6) What is the source of the voltage reading (connected to alternator or straight to battery?)

I took a quick look, but need to do a more careful look to see if there are any sensing wires that didn't get hooked up to the batteries during commissioning. Otherwise I'm starting from square zero. The wire bundles are a dense maze. Alternator output and battery health are fine. This is purely a sensor/gauge issue.

Thanks for any advice to get started.


p.s. cross posted to yahoo mainship group

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Old 08-05-2019, 12:30 PM   #2
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City: Sassafras River, Maryland
Country: USA
Vessel Name: Seventh Sojourn
Vessel Model: Mainship 400
Join Date: Mar 2018
Posts: 188
I also have this issue. Did you ever figure it out?

Gary Armstrong

The man who goes farthest is generally the one who is willing to do and dare. The sure-thing boat never gets far from shore. Dale Carnegie
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Old 08-08-2019, 09:10 AM   #3
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City: Westerly, RI
Country: USA
Vessel Name: N/A
Vessel Model: 1999 Mainship 350 Trawler
Join Date: Jan 2014
Posts: 2,391
My fuel gauges have a switch to toggle between the upper and lower helm. I can't display fuel levels on both the upper helm and lower helm gauge simultaneously.

Is it possible that one of the helms has a transfer switch?
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Old 08-09-2019, 06:11 AM   #4
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City: Carrabelle, FL
Country: USA
Vessel Name: Morgan
Vessel Model: '05 Mainship 40T
Join Date: Jan 2008
Posts: 1,462
My port side volt meter on the upper helm is also inoperable, though the lower helm works fine. So I'd love it if someone found a solution here.

In general, I've found the faria gauges Mainship used to be really bad. My upper stb tach bounces around all over the place, sometimes off by as much as 600 RPM. I give it a little rap with my knuckles and it bounces back into place. Not real confidence inspiring as far as accuracy goes.
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Old 08-09-2019, 06:23 AM   #5
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City: Maryland
Country: USA
Vessel Model: 42' Sportfish
Join Date: Aug 2013
Posts: 5,204
Our boat came with Faria gauges. The tachs are "rebuildable" when they go bad, but engine hours (if included in that model tach) get reset to zero. Maybe their other gauges are rebuildable, too.

The analog tachs were also calibrate-able. Sort of. At one RPM level... and then not all that accurate at opposite ends.

I went through that goat-rope on both tachs, then finally replaced them with Aetna digital tachs... and once the fual gauges started acting up I replaced all the other gauges with CruzPro digital gauges. (Aetna's tach fit the existing 4" hole, otherwise the CruzPro tach would likely have been fine too.)

South River, Chesapeake Bay
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