1992 Mazda MPV fuel gauge

Locate the plug for the fuel pump/sending unit. It may have four wires--two for the pump and two for the sending unit (the sending unit wires will probably be smaller). Use an Ohm meter and check the resistance from the sending unit. Have a couple of gallons of fuel handy. Take the test before adding the fuel and after adding. The reading should be different. If not, or if you get no reading at all, you will need a new sending unit. If all checks out post back and we'll go from there.