What do I need to renew my 8 year expired French passport ?

It looks like you just need to go to the consulate (make an appointment first) with your expired passport and two new passport photos, proof of current residency in the US or otherwise, since it expired more than two years ago you'll also need a valid French identity card or certificate or declaration of acquisition of French nationality, a naturalization certificate or the French long-form copy of your birth certificate.
I'm not sure what if any forms you need specifically, but I believe there is a fee for the renewal.

If for some reason you can't go to the consulate contact them via telephone and I get the information on how to do a mail in passport renewal.