Fuel gauge not reading correctly/consistently/at all (engine-swap content)
 

The fuel gauge isn't reading correctly/consistently or at all on occasion & there's no consistent pattern to it that I've been able to figure out after 4 months of driving around in it. :wallbash:

A few facts to give background to this...

- I've swapped a 13B-MSP 6-port & running gear from a Series 1 RX8 into my MK3 MX5/Miata
- The clocks are the RX8 ones (thankfully the 2 connectors are the same but the wiring is slightly different for a few things which we've sorted so-far)
- The fuel pump & sender are the RX8 ones (I know there's a 2nd sender on the other side of the RX8 tank) with the fuel tank lid being the MX5 one; a custom-engineered job has been done to fit the RX8 lower fuel cradle to the MX5 upper fuel cradle lid but the connectors from the tank-side to the top-side are the same.

Two main questions:
1) What parameters, signals, etc does the fuel gauge need to read correctly?

2) Can the 2nd fuel sender in the non-pump-side of the tank be emulated somehow using only 1 side sensor+wiring?