Gas gauge/Sensor

[BnObob]

I have a problem with the fuel meter on a 1989 300E sedan. At about 1/2 full,
the needle jumps: E, F, wherever. When it goes below 1/2, it settles down.
[I had a similar problem in an old 115 body 240D, and lifted the trunk mat,
unscrewed the sender, disassembled, cleaned the gunk, the nichrome slide
wires, and cleared the problem.] But on this 300E, where the tank is the support for the rear seat, I cannot find access to the tank, nor sensor.

I suspect access is through the trunk. I have only the Chilton books, not
a real Mercedes CD/manual. Can anyone tell me if the sensor is the suspect,
and how to locate/remove the assembly?

Thanks.....

[MTI]

The tank is accessed from the trunk, remove the carpet wall that is beneath the rear window and you'll see it. The tank sits vertically and was placed in the rear of the trunk for safety, since the trunk crush zone would prevent it from being ruptured. The sender is the large bolt cap with the sender wiring at the top of the tank.