2003 Toyota Highlander 6 cyl Two Wheel Drive Automatic 50000 miles
Whenever I open the gas tank of my Highlander, it makes a " swoosh" sound. Sometimes it's fairly quiet, sometimes much louder. Although the car manual says that is normal, I've also been told that this sound indicates that there is vacuum in the tank which could make engine work harder to suck in the fuel. In addition to the " swoosh" sound, after I pull out the nozzle from the tank when putting gas, there is a gurgling sound as if the gas is running down into something (think of a sound a partly-clogged sink makes when draining). I've not seen any leaks under the car and there is no gasoline smell but the noises are troubling me since they were not there before. My car is 6 cylinder and has 50.000 miles on it. I haven't had any other problems with it.
I'm a college student with minimal income so I would like to know if this is a seriuous problem, what I should expect to be told regarding repairs if I take my car to a mechanic (change filter in the tank vs. Change the whole tank) and the approximate price of the possible repairs. Thank you very much!