Fuel Tank Suddenly Takes No More Than 7 Gallons...

Greetings~

We have an 05 with 160,000 miles on it. In December, we took a trip from SW Wisconsin to New Mexico. Along the way, in some situations where it was very cold, I noticed that the gas pump would automatically shut off as if the tank was full, even tough I knew it was near empty, and this was happening even at very slow fill speeds. I also noticed that I could never get the tank to take more than 7 gallons or so. The auto shut off issue happened several times on the trip but now rarely if ever happens, but I still cannot put more than 7 gallons of fuel in, and this last time I filled when my gauge was at one bar, I got to 7.2 gallons, auto shutoff of the pump occurred, I tried again very slowly to top it off, auto shutoff happened right away, then when I started the car the gauge still read one bar shy of full. This is maybe the first or second time this has happened. Generally the gauge reads full after 7 or so gallons up from reading at one bar after filling. Also, in the summer we were easily driving over 500 miles on a tank. Now we are lucky to drive 300. I have heard the the tank is not solid, but is a bladder of some sort? Or contains a bladder? Makes me wonder about air displacement, or if the bladder is too stiff in the winter, or is somehow defective? The car was in at Toyota recently for a couple of recalls, and they couldn't find anything wrong with the fuel system without charging me the $99 to go in and reset it. Anyone have any thoughts?
Thank you,
Peter.

 

I know how to search quite well thank you. I ran a query for fuel tank and found very little, hence my post.

 

Thank you~ I have found that out by accident a few times! I did just search the forum with only the search term "bladder" and got quite a lot on the subject. It was not the first word that came to mind when wanting to learn more about this.
Peter.