Both gauges have power, a ground and a sender wire. Sounds like the Tilt is working, its just the sender is grounding out. The gauges require 240 ohm (down or empty) to 33 ohm (up or full) senders. If the sender wire is grounded the gauge shows up or full.
The tilt gauge bottoming out probably means the sender has opened up and there is no connection. Either that or the gauge is bad
This is the fuel sender but the trim is the same