2003 Hyundai Elantra Check Engine Light

I was wondering if anyone has had a problem with the check engine light coming on.... a lot... Since last August, my check engine light has come on 9 times. 1 time it went off on it's own, other than that I have taken it in to the dealership where I got it, and they normally have it for hours and have checked, so they say, everything, they've changed the fuel pump, and some other things, I can't really remember what... it's happened too often. They first said it was because my gas cap wasn't on tight enough, and that it has to click at least 10 times. (People look at me wierd at the gas station because I make sure I do that) They said not to top off... I don't... so does anybody have any ideas, or suggestions?

Thank you!

First off what was the codes they got????
Sec yes you must turn the gas cap 8 to 10 clicks
to help to cut down on evap codes

They didn't tell me any codes... the only thing they've told me that they've done is replace my fuel pump. And that I have had a couple evap. leaks...
And for the clicks on the gas cap... if it is so many times, why would they put 3 on the cap? Just wondering...