Grilled Citrus Prime Rib

Mix together all ingredients, except roast, in a medium mixing bowl. With fork, pierce holes into roast and place in a large resealable plastic bag. Pour marinade over roast, seal bag, and allow to marinate in refrigerator for 2-3 hours. Preheat grill for medium-low heat. Remove meat from plastic bag and reserve marinade. Insert meat thermometer into roast. Add wood chips according to manufacturer's recommendations. Place rib roast on grill rack. Be sure to have a drip pan filled with an inch of water underneath. Cook for 2 1/2 to 3 hours, adding fresh wood chips every 30 minutes, and brushing with reserved marinade for first half of cooking time. When done, remove roast from grill and let stand for 15-20 minutes before carving.