I would first keep a log of all of her interruptions for a few days. This way, once you start telling Susan "no", if she goes to her manager and says "Bluuuuuuue won't heeelllppp meeeee!!!!" you can authoritatively say Susan was interrupting you 17 times a day asking about a,b,c which aren't your job, and x,y,z which are utterly basic job skills she should already have.
Once you've got a few days logged, it's time to start clearly telling her to knock it off:
"Susan, I really don't have time for all of these interruptions. If you need additional training, go ask your manager."
"Susan, I'm trying to work here and I don't have time for all of these interruptions. If you can't figure it out, go ask your manager."
"Susan, I don't have time for all of these interruptions and I'm not even the right person to ask. Go talk to your manager."
"Susan, please go ask your manager and leave me alone. I've got my own work to do."
She sounds exhausting! Hopefully a broken record of "I don't have time for your interruptions" instead of "I don't know" will shut her down and/or redirect her to someone else to pester. And in case someone says you're not being a team player because you're not constantly 'helping' her, your log will demonstrate that she's the one who is way out of line and disrupting your work.