I get your question... The Black is the power, Blue/white is the feed power to the tank, and the yellow is the return to the gauge. I don't have a headset to see where they go on the gauge tho.
Check what I told you with a test light to confirm the power feed. Key on, and engine off. One will light up, and Duh... That is the power.
You can open the gauge housing to trace which do what from there. Two will go straight into the coil on the needle, and the last one (power ) will go to the gauge wire that is jumped into one of the needle coil wires.
I HOPE that helps.
