In a small saucepan, combine pineapple with juice, Gravy Master, mustard, vinegar and water. Simmer 5 minutes, stirring frequently. Remove from heat. Grill chicken pieces 4 to 6 inches from hot glowing coals for 15 minutes, turning frequently. Brush with prepared pineapple sauce and continue grilling for 15 minutes longer, brushing frequently with sauce. Remove from grill and serve immediately. Heat and serve remaining sauce separately.
Makes 4 servings.