GRILL DIRECTIONS: Heat grill. In small bowl, combine barbecue sauce, syrup and liquid smoke; mix well.
In medium bowl, combine ground pork and 3 tablespoons of the barbecue sauce mixture; mix well. Shape mixture into 4 patties, 1/2 inch thick.
When ready to grill, place patties on gas grill over medium heat or on charcoal grill 4 to 6 inches from medium coals; cover grill. Cook 10 to 12 minutes or until patties are no longer pink in center, turning once.
Meanwhile, place pineapple slices and buns, cut side down, on grill. Cook 1 to 2 minutes or until buns are lightly toasted. Turn pineapple slices; cook an additional 1 to 2 minutes. Place patties and pineapple slices on bottom halves of buns; drizzle with remaining barbecue sauce mixture and cover with top halves of buns.