To find it, you'll need to:
1. Consult a repair manual: A Chilton's or Haynes repair manual specific to your 1990 Chevy Lumina will give you the most accurate location and diagrams.
2. Look near the fuel tank: Start by looking along the fuel lines running from the fuel tank towards the engine. The filter is usually a cylindrical canister in the line.
Be aware that fuel is under pressure in the lines, so be extremely careful when working around the fuel system. It's advisable to relieve pressure before attempting to access or replace the filter.