I understand what you mean Charles and you are right, the range for full to empty for the 250mm sender is 2.5 to 72 ohms and for the 280mm unit it is 2.5 to 75.5 ohms, so not quite the same and theoretically the contents may well show about the same for both at a given level. The reality of it is that if you replace the 250 unit with a 280 one, with the fuel level staying the same, the indication shows about 20% more with the 280 sender. My contents now shows 0% after about 190 to 200 miles from full rather than about 120 or so with the 250mm unit.
Does this mean the fuel gauge is calibrated to read 0% at 72 ohms then? Can it be recalibrated to read 0% at 75.5 ohms My 280mm sender reads 0% after 160 miles though.
