RE: Fuel gauge calibration
Sometimes, ethanol can build up on the fuel sender "card".
Running Techron additive in the tank can clean the ethanol off.
Would you please define "fuel sender card" I've not heard of this item before. Also how would ethanol get in the diesel fuel of the OP's fuel tank?
Richard
Sorry. Didn't realize the OP had a diesel.
Fuel sender card is the resistor/circuit board that the float makes contact with.