My guess is that it will work. There should be two wires coming from any particular gauge. Your NMEA gauge is connected to the power probably through the ignition switch and then has one wire connected to the sender on the tank.
The tank then has a second wire to ground. To add an analog gauge you just need the gauge with it's data wire (analog) connected to the same spot as the NMEA gauge. The power wire for the analog gauge can be connected whatever 12v power source you wish. It can be connected to a separate switch or to one of your existing switches on your panel. I have mine connected to the same switch as my radio/gps. This way when I am fueling I don't need the ignition switch on to see the fuel gauge.
I don't see why this won't work. The only hiccups might be that the resitance range on the gauges might be different, which I can't necessarily explain what conflict this might give.
I might try it myself. I think the gauge for my yammy will do fuel. I've just never bothered to hook it up.
If you haven't drilled the holes for the new gauge yet you might consider putting the analog gauge on a separate switch near your fill port. This can be handy to avoid the dreaded overfill especially if you are filling on the water.
Originally Posted by jlanng
Can I do this? I've got an NMEA2000 fuel level sensor so I can see the fuel level on my chart plotter. I'd like to retain the existing gauge in case the plotter breaks down. Is it possible to wire them both up, or should I install a switch?