GM fuel tank in mazda gas gauge question

I'm running a fuel tank from an 83-85 S10 blazer in my mazda and can't get the fuel gauge to work at all. When I ran a GM fuel cell the gauge read backwards but now it does nothing. The sending unit is brand new and it should be the 0-90 ohm like the cell was. I'm going to bring my meter to work tomorrow to test it. Any suggestions?

try reversing the wires for the fuel level

Does the temp gauge work?
If not, check the fuses.