Preheat oven to 350. Spray 3 9x1 1/2 inch round baking pans with no stick spray; set aside.
Stir together flour, baking powder, cinnamon, baking soda & salt; set flour mixture aside.
In large mixing bowl beat sugar, oil & vanilla with electric mixer on medium speed until combined. Add eggs, 1 at a time, beating after each addition. Add flour mixture alternately with sweet potatoes, beating well after eac addition. Stir in pecans.
Spoon batter into prepared pans. Bake 35-40 or until toothpick comes out clean. Cool in pans 10 minutes. Remove from pans. Cool completely.
Spread pineapple filling between cake layers. Frost top and sides of cake with cream cheese frosting. Store in refrigerator.
Pine apple Filling: In saucepan combine 1 can (20 oz) undrained crushed pineapple(juice pack), 1 cup sugar and 2 tbsps cornstarch. Bring to a boil; boil 2 mins. Cool