wiring new fuel sender to digital speedometer and fuel meter

I have a 1991 Grady White with a 2003 Yamaha 175 HPDI. The gas gauge on the digital speedometer indicates the gas tank is empty even though the tank is full.

I suspect the fuel sending unit is malfunctioning. Do you have any suggestions?

If I replace the fuel sending unit, do you have a wiring diagram to connect it to a Yamaha digital speedometer and fuel management meter?

[boats.net]

The fuel tank sender wire(usually pink) connects to white wire on speedo. You can ground pink wire at tank sender with key on and gauge should read full, if not then it has bad wiring or bad sender.