Place pork roast in slow cooker. Cover and cook on LOW 10 - 12 hours or on HIGH 5 - 6 hours or until done.
Remove pork roast from slow cooker. Discard cooking liquid. Shred pork with 2 forks. Return pork to slow cooker. Add barbecue sauce, lemon juice, brown sugar and onion. Cover and cook on LOW 2 hours or on HIGH 1 hour.