Return of the Living Dead III (1993) starring Kent McCord, (Melinda) Mindy Clarke (perhaps better known as Lady Heather of "CSI: Las Vegas"), J. Trevor Edmond, Sarah Douglas / IMDb synopsis: Curt loves Julie, so much so that, when she asks Curt to break into his father's top-secret Army test center, he agrees. What they discover is that the military is testing the zombie gas to see if it can become a usable bioweapon. The teens escape after letting one of the monsters loose. In the midst of blind panic, Curt crashes his motorcycle, killing Julie. Deciding he can't live without her, Curt again sneaks onto the base to use the gas on Julie. However, Julie begins to act strangely. After she takes a bite out of a gang member, the two of them are pursued.
She does do that: pierce herself with glass and metal. Images are readily found on the Net if you type in "Mindy Clarke Return of the Living Dead III" and search Images.