1. Preheat oven to 325°.
2. Coat a 10-inch tube or a 12-cup Bundt pan with cooking spray. Sprinkle with flour; shake out excess. Sprinkle chopped pecans over bottom of pan.
3. Combine cake mix and next 5 ingredients (through rum), mixing well, according to package directions. Pour batter over nuts. Bake 1 hour or until a wooden pick inserted in center comes out clean. Cool completely.
4. While the cake bakes, make glaze. Melt butter in saucepan. Stir in the sugar and water. Boil 4 minutes, stirring constantly. Remove from heat. Let cool 1 minute. Stir in rum.
5. Invert cake onto a plate. Pierce top of cake in several places. Brush glaze evenly over top and sides, so cake absorbs glaze.