Fuel gauge issues

[mauro12]

Hello guys, I have something wrong with my fuel indicator , here I explain you in details . When put some gas , the level increase but after sometime the level drops on the empty part. If I turn off the engine and on again , the lever indicate the right amount of gas but after sometime I have the same issue once again. Do you think is the sending you defective that maybe needs to be cleaned ? Maybe replacing with A new one it will solve forever this issue ? I have seen many pagodas and I have to admit that the fuel indicator has always been not 100% accurate in the readings, especially when you park your car uphill and sometimes the Level jumps all the time .
I have a 250sl early model, I read that the 230sl have another sending unit which is NLA now .
Thank you for your help .

[ja17]

The early cars used a lever type with a float at the end of the lever. Most W113 in later years used a cylindrical unit. A float housed in a cylindrical housing moves along resistance wires. First step is to remove it. It is fairly easy since it can be removed with the tank in place. Access is through an opening in the trunk floor. Once lifted out identify it. You can also rotate it which will cause the float to move and if you have the ignition on your gauge should respond accordingly. Caution, cover the open fuel tank while testing your gauge. Open fuel is a fire hazard. A static spark or electrical spark can cause a fire.

[mauro12]

This symptoms are usually from the sender unit being dirty ?

[WRe]

Hi,
maybe this can help: https://www.sl113.org/forums/index.php?topic=31224.msg226551#msg226551.
...WRe

[Pawel66]

This symptoms are usually from the sender unit being dirty ?

Could be and reading is also sensitive to electrical connections being clean. Higher resistance - lower fuel level.

[mauro12]

the red low fuel light depends on the sender unit too? if it doesn't work you need to replace the sender unit ?

[Pawel66]

Yes, it does. There is a separate wire for it but it is switched on by sender.

Bulb is the suspect as well.