Hi, I need help. Lately my fuel tank does not completely fill up. It stops around 17-18 gallons. Can anyone tell me what could be causing this? Thanks,

 

It's the fuel relay module.

My 2001 E320 exhibited the same behavior (never able to get a reading showing it is completely full, but you know it is), and that fixed it.

This happed around 17k mi if that is significant.

Regards,

David

 

shouldn't the tank be full at 18 galons?

what is the capacity of your tank?

 

Capacity is 21 gallons. It really does not seem to be full.

 

3 galons difference. if your fuel tank type is for ski rack, then it can't be 21.