Testing of Fuel Management Gauge

[<Jim>]

I have a fuel management gauge on twin 150hp's and recently replaced it, it worked for a total of 70 gallons and stopped working. Is there a way I can test the gauge itself by connecting to 12 power source to see if it will run through test sequence? The backlights work, but there is nothing displayed on the LCD, and there is power to it from both yellow and red.
Thank You.

[<boats.net>]

If you have 12 volts to Red and Yellow and good ground to black it should work unless the gauge is bad