yamaha multifunction speedometer fuel level issue

[carcrzy812]

i have twin f115 4 strokes and have an issue with the fuel level not working on my gauge. sending units are new, wiring is good and selector switch is good(2 tanks) i am reading the correct resistance between ground and the sending unit wires all the way up the the gauge. it is hooked to the white wire coming off of the speedo. that wire is not grounded, but it seems like it should be(how else can it determine resistance). could the gauge be bad? or am i missing another connection somewhere.

the selector switch is set correctly for us(30-230ohms)

hope someone can help

Frank

[boats.net]

Ground white wire at speedo and turn key on, guage should read full, disconnect white wire and should read empty. If doesn't gauge is not working.