I believe that there should be a hose between the senders from one side to the other to keep an even fuel level. Also, the senders are wired in series, so if one goes bad it might still show a half tank when it goes empty. Maybe reach your arm inside the tank with the sender removed and try to find the crossover hose.

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Alex
MB Star certified, now independent.
Owner/Operator FDMotorsport Mpls. MN
Mercedes and GM certified transmission rebuilder
We all need a little help sometimes...

1998 E320 4MATIC-- stolen by my sister
1989 300TE-- sold
1999 C230 Kompressor