Fuel guage could be a bad sending unit (in tank), float that isn't floating (also in tank), bad ground, or bad wire(s) between sending unit and fuel gauge, and of course bad fuel gauge. The temp sensor shouldn't have anything to do with the fuel gauge.
Typically there's a 2 or 3 wire setup. One sends a power signal to the sending unit. This should be either 5 or 12 volts, but someone here may know the specific number you want. The float is attached to a resistor that modifies this signal and sends it back to the fuel gauge on a second wire. If there's a third wire, it will be a ground. I would do a continuity test on all wires to the unit to verify they are unbroken, check voltage in, then verify ground (if applicable.)
You can test the float by putting it in liquid (I recommend gas in a clear container to avoid cross contamination issues) and seeing if it floats. If t doesn't you may be able to replace the float, but if I already had it out and any part of the unit was suspect, I would replace the whole assembly. You can test the resistor by attaching an ohm meter between the input wire and output wire and actuating the float arm manually. You should see the resistance rise and fall smoothly. If it's open at any point you have a dead spot and the unit is bad - you may be able to get just the resistor, but see recommendation above.
If you suspect you have a grounding issue you'll probably find it was a body ground. DO NOT just clean this area up and reattach it to the body. It will rust out again, and you'll be pulling the tank again to re diagnose it and fix the same problem. Run a dedicated ground from the battery to the unit. In fact, if you're going to have the tank down, do this anyway just to prevent it going wrong in the future. Oh, don't thank me for the dedicated ground advice, thank JeepHammer and the OP of this thread:
Until I read that, my dumb @$$ would have just cleaned up the ground and reattached it. Now I know better.
Now, if you've checked all of that, run your dedicated ground if applicable, and done the same for your fuel gauge because Jeep loved their body grounds, and your fuel gauge still isn't working it's the gauge itself or you're just out of gas. Don't laugh, I've seen customers do it. It's usually the most expensive 2 gallons of gas they'll ever buy, because it comes with a dealership markup and at least a half hour diagnostic fee. But they learn to read their fuel gauge real quick.