Float type fuel sending unit.

[Ricochet]

Hi, Newbie here from the Middle East. I have recently replaced the tank (65L Danske) on my ‘64 230SL and now the fuel indicator does not work. I have removed the sender unit and the indicator works perfectly - empty to full by hand but once I insert it back into the tank - nada. On power on the needle flickers and remains at empty. Any idea? Don’t expect it’s grounding as I have held the unit in my hand off the car and operated it and indication works fine - any ideas?

[lpeterssen]

Dear Ricochet

Check ground connections at the ground floor next to the wheel arch. That is the source of gro7nd for the fuel sender unit.

Best regards
L.peterssen

[lpeterssen]

Also it is common, if the car is still running on its original wiring harness, that the cables at the fuel sender connector, two are blue and the ground (brown) are brittle.  Check those inside the connector as well. One may be broken there.

[doitwright]

There is a float inside the tube. If the float is not floating you will get the results you describe. There are youtube videos that show how to disassemble the sending unit and how to check. Porsches of the same era use the same type of fuel sender.