With the Low fuel light on & the gauge on the Last line, when fuel is added, the total number of gallons received is 13.5gallons, the manual states that the tank holds approx 17.1gallons which suggests that there is 3.6gallons remaining in the tank. My question is can the dealer "adjust" the fuel sending meter to reflect a more accurate reading?
The fuel sending circuit has been replaced, the problem still exists & the dealer is of further help.
INACCURATE FUEL GAUGE on 2008 Acura TL
If with the low fuel light on & the gauge on the last line you are able to drain the fuel tank and 3+ gallons of fuel are recovered you are correct.
The factory diagnostic tool , or "scanner" , probably has the facility to adapt the gauge reading within a given range.
Consider the possibility that the total volume of the fuel tank is not accessible to the fuel level sensor or beyond its range by design.
Don't have an answer for you, just wanted you to know that you're not crazy....