Re: XF-ZL Fuel Guage Wiring
I'm not 100% sure, but it is likely the two are not compatible. The old ZD probably had a float and arm type fuel sender which only uses one wire to the gauge. The XF certainly used the "floatless" sender that has no moving parts at all. It is just a printed circuit board with two (three??) tinned solder strips on it that is immersed in the fuel and has the three wires conncted to it. I've always wonderd how they work, I think it is on capacitance which means there is some electronic intelligence up in the dash.
I'm prepared to be proved wrong, but I think you're stuffed, so to speak. Good luck!
BTW, can anyone tell us how the XF (and later) senders sense the fuel level?