2004 Forester XS
5 speed manual
I always fill my tank when I am between E and 1/4 tank.
I drive basically the same route every day at the same speeds, etc. (Mostly two lane back roads at about 60mph with few stops)
Sometimes I get 18 MPG, sometimes I'm pushing 30 MPG.
When I fill up, I fill up all the way. Sometimes it takes 8 gallons, sometimes over 11 gallons despite filling up when the gauge is at the same place every time.
I may have a rust hole in the filler neck of my gas tank. I'm not sure. It would explain my check engine light that is on for an evap leak (same thing as loose gas cap). However, no gas seems to leak out when I fill up.
Is my mileage really fluctuating that much? If so, why?
Is my fuel gauge reading inconsistently and therefore making me think that I'm filling up at the same time when I actually am not?
Is the pump shutting off at different times because of a rust hole in my filler neck? My gas gauge often reads Full for as much as 70 miles, so I could be less than full, but the gauge is showing full.
It just occurred to me to start filling up at the same odometer reading instead of the same fuel gauge reading for a little while. Maybe if the fuel economy appears consistent, I can rule some things out.
Anyone ever have a similar issue?
General thoughts and opinions?