*Edit: Don't worry i found out how*

But i need to know how to get a full citizen pass to enter the vault (not a fake one)
i took some test but he failed (his science is only 28%)

Shoot your way in. You don't want to be attached to those people.

is their any other way to get in without doing the citizen test?
i talked to some guy who talked to the girl you show your vault suit and drink carton to prove
you are a vault dweller, but when i do she just tells me to take the test !?

i will probably get owned if i take them on

Good luck shooting them.

To get your Full Citizenship, you must work for Lynette. If you can finish the task she gives you, you'll have full citizenship. The task involves a certain factory north of Vault City called Gecko.
Good luck!

Lynette isn't anything a bozor won't fix.

Seriously, I don't recall the several ways to get in there, but you can get the citizenship from Linette, the council member, and the test.

Kill Lynett on your way out...you know you want to.

If you get the Citizenship from McLure (or what was his name) , avoid talking to Lynette, she may remove it from you. For reasons that you will understand after and during the quest.

http://www.gamefaqs.com/search/index.html?game=fallout+2&platform=0

This will help

If you avoid her, you'll never become captain of the guard.

toggle combat on before the gates of the vault and run in (dont attack anybody) if you are in combat guards cant initiatiate dialog with you so you can pass by them