The fuel gauge on my '91 Town Car doesn't work, at all. Can that be fixed by replacing a fuse?

sounds like you may have a instrument cluster panel problem and will have to go to a shop that can fix it. its possible that there is a contact problem with the cluster to body connection.

You can look under the hood in the big black box at the fuses and relays.I didn't find any link between the door lock, the wipers and the fuel gauge except the body computer. They have rebuilt ones and they have to program it to your car

You have blown a fuse..check fuse box. There may be one fuse box one in the cabin but also check for the fusebox in the engine compartment.

The fuel gauge is not fused separately from the rest of the gauges in the instrument panel, so unless the whole lot is dead the problem lies elsewhere. It is likely if the gauge doesn't work it will be the gas gauge sending unit in the fuel tank that is defective.

Talking about fuel gauge issues and how do you how do you diagnose, ... is the dash unit right here, and obviously the gauge doesn't read correctly. ... to fix the fuel gauge, so you can actually fix the fuel gauge electronically by reflashing the program. ... How to Troubleshoot a Malibu Fuel Gauge & Dash Light Not Working ...Could be a bad fuse - fuse # 17 is a 15 amp fuse for the fuel gaugeCould be a bad float on the fuel gauge sending unit inside the gas tank ( it's with your electric fuel pump ) If the float gets a pinhole or crack in it , the float fills with gas and sinks so the gas guage reads empty all the time Could be a wiring problem

maybe you bent th float arm. Did you replace just the pump or pump/sender assembly? Ford or aftermarket? Or a bad sender/pump assembly

Turn the ignition on and off several times before inspecting the gas tank because a blown fuse is the usual cause for fuel gauge malfunctioning. If the gauge remains motionless, check your fuse box and determine the fuse's location using your service manual.
Replace the fuse if the link is broken or damaged. Then, inspect the gauge's wire connections for cleanliness and make sure the wires are connected.
Turn the ignition switch to the "off" position. Attach one end of a jumper cable to the fuel-gauge terminal behind the gauge itself. Attach the other end to the ignition terminal.
Replace the sender unit in the gas tank if the gauge reads full and your car does not have a full tank. Replace the fuel gauge if the needle remains inoperative.

Hello and welcome to FixYa!
As a first course of action, please do check the fuse. If the fuse is blown, the fuel gauge won't work. If that's the case, please replace it.
If the fuse if good then the problem will be on the fuel float itself. The fuel float is located above the fuel tank. You will need to pull down the fuel tank to gain access to the fuel float. Once replaced, the fuel gauge will work normally again.
Hope this helps and thank you for using FixYa! Have a good one!

99% of the time this is due to a defective gas gauge sending unit, this is located in the gas tank.

Go to Autozone and purchase a Clymer repair manuel. It will show how to remove the dash. You need to find all the screws.