Mix cake mix, sugar and margarine together until crumbly. Sprinkle over filling. Sprinkle pecans on top.
Bake at 350 degrees 1 hour 10 minutes. Serve warm with whipped topping.
*check doneness with a toothpick around 50 minutes to account for variations in ovens and avoid burning the cake. The cake is done with the toothpick is clean when inserted in the middle.