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Fuel (Gas) Send Unit aka fuel level float

Posted: January 28th, 2024, 11:47 am
by kgarguilo
In my quest to have more information available to me while I am away, I just installed a Victron Cerbo GX. Btw, very cool. My next add on is to monitor my fuel tanks via the Cerbo that appears on my MFD Garmin 8612 Plotter.

I am trying to identify what kind of Fuel send units are on my 1999 Carver 406. Meaning manufacturer and specs. The only number I see on the 5 hole mounted send unit is 3349-17 A9.

Tank Model.jpg

Fuel Send Model.jpg


Ultimately The tank level ports on the Cerbo GX can each be configured to work US tank senders (240 - 30 Ohm) standards; or to configure a custom Ohm resistance range between 0 Ohm and 300 Ohm (requires firmware v2.80 or higher). The tank level inputs are resistive and should be connected to a resistive tank sender. The built-in tank sensor connections do not support mA or 0-5V type sensors, this type will require additional accessories or replacement with a resistive type sensor.

In short, I need to know if my Fuel Sender is Resistance or mA / 0-5v It would be ideal if the specific range of resistance was known. Or, any idea of the manufacturer? Google is leading me down too many rabbit holes without specific knowledge. As always, any help would be greatly appreciated.

Re: Fuel (Gas) Send Unit aka fuel level float

Posted: January 28th, 2024, 12:07 pm
by bud37
What does it say on the red sticker......there is a nominal resistance number there perhaps.
I have connected Garmin to tank sensors before, just not on a Carver......just connected to the tank terminals at the connection panel and if I remember right all I had to do was tell amts etc after the tank was filled....it has been a few years since that so a bit cloudy. That boat I had installed a complete Garmin backbone thru out though.

Sorry if this is not helpful but all I can remember about it.

Re: Fuel (Gas) Send Unit aka fuel level float

Posted: January 28th, 2024, 12:43 pm
by kgarguilo
postby bud37
What does it say on the red sticker.


Oh, crud, I thought that was a warning label and it did not appear to give that info. See close up. 240-30 Ohms. It looks like I can hook it up with some tinned wire after all. Thanks for pointing out to me. I really missed that one.

Re: Fuel (Gas) Send Unit aka fuel level float

Posted: January 28th, 2024, 1:35 pm
by bud37
Good stuff....that info is generally on these things somewhere.

Re: Fuel (Gas) Send Unit aka fuel level float

Posted: January 28th, 2024, 11:03 pm
by g36
You going to monitor all 4 fuel tanks? What else you gonna do with the cerbo?

Re: Fuel (Gas) Send Unit aka fuel level float

Posted: January 29th, 2024, 9:57 am
by kgarguilo
Initially I was going to use it for the Ruuvi Temp sensors, I have purchased 3 and placed them where all my bilge heaters are located:
    Engine Room
    Aft cabin under bed
    V Berth cabin under bed
Additionally it was for monitoring my Victron Skylla IP65 12/70 monitoring (btw very cool to see away from the boat)
Since the installation went so easily, I figured let me look at the fuel tanks, apparently they are also easy since bud37 pointed out the info I needed was on the red tag. So today, I will be hooking up one fuel tank to test and see if it works (using tinned wire 18 AWG) If it does connect and seem to work I will do the following tanks:
    Port Fuel (Gas) 97 gallons
    Starboard Fuel (Gas) 97 gallons
    Aft Fuel (Gas) 145 gallons
    Fresh Water 70 gallons
There are two relays, Analog and digital I/O that can make things happen but no idea on a use case for them just yet. Any suggestions are welcome.

Re: Fuel (Gas) Send Unit aka fuel level float

Posted: January 29th, 2024, 11:09 am
by g36
Sounds like your having fun. My 405 has 2 aft tanks. You say your 99 has only 1 aft fuel tank? Knew the 355/356 had 1 large , just figured 406 would be the same as mine.
Yep I have ways to remote monitor things on my boat too. Interesting to see what others do too. Once all set up please post