I have 93 and 94 940s. Both of them had fuel gauge failures caused by these problems:

1. The flex circuits on the back of the Yazaki cluster can fracture. These can be fixed by resoldering and possibly adding jumper wires. Fractures are not necessarily at the fuel gauge screws. I had to use an ohmmeter (cluster unpowered) and voltmeter (cluster powered on workbench) to discover and fix all the fractures. See the FAQ and link to Turbobricks.

2. The fuel gauge itself contains a circuit board with soldered parts. Some of the solder joints can fracture and must be resoldered. I removed the gauge and resoldered every thru-hole connection on the circuit board.

On my cars, both of the fixes above were necessary to restore the fuel gauge operation. I would look for problems with the Yazaki cluster flex circuit first. It is possible to test the instrument cluster with the cluster sitting on a workbench. A 12v power supply and some resistors to simulate the fuel sender unit are needed. That is how I discovered and fixed the fractured Yazaki flex circuits.

If you are concerned about soldering, perhaps try to find an electronics hobbyist who is familiar with the use of a small soldering iron.

It is helpful to connect an ohmmeter to the ground and fuel gauge sensor wires at the instrument cluster electrical connector. Make sure the resistance of the in-tank fuel sender unit is stable (see the FAQ). This rules out a fuel sender unit or wiring problem.

Regards,

Mike