The fuel filter on a 1991 Buick Skylark is located
in the fuel line, usually near the fuel tank. However, it's not easily accessible and is typically
not visible without removing other components. You'll likely need to consult a repair manual specific to your 1991 Buick Skylark to get the precise location, as there might be slight variations depending on engine type and options. A Haynes or Chilton manual would be very helpful for this.
Trying to find it without a proper diagram risks damaging fuel lines or other components.