It's a composite float and rarely fails .

The sender is directly underneath the first aid kit on the rear parcel shelf, use a stubby #2 Phillips screwdriver to remove the single screw then gently tip the plastic tray up and out, set aside .

Peer in the open hole, there's a square black plastic plug with three wires, wiggle it with the key on and see if the gauge moves .

If not, the sender comes out easily with either a LARGE pair of Water Pump Pliers (nee: Channel Locks) or a 46MM socket .

I've forgotten the wire colors , you bridge two of them to force the gauge , someone here will explain .

The sender is a long aluminum tube with extremely delicate wires inside, if you need to open it to look, use a small pin spanner or, like everyone else including Dealer Mechanics, a pair of pliers to gently squeeze the brass nut's plastic surround *just* enough to where you can unscrew it then the bottom comes off followed by the aluminum tube, revealing the float and delicate wires .

BE GENTLE if you decide to try cleaning the wires ! .

Because the gauge doesn't move at all I doubt the sender's at fault but now you know what to do .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better