Preheat oven to 350 degrees F (175 degrees C). Lightly grease one 9×13 inch baking pan.
Combine the pumpkin, evaporated milk, eggs, sugar, pumpkin pie spice and salt. Mix well and spread into the prepared pan.
Sprinkle the yellow cake mix over the top of the pumpkin mixture and pat down. Sprinkle the chopped pecans over the top of the cake mix then drizzle the melted margarine all over the top.
Bake at 350 degrees F (175 degrees C) for about 1 hour but no longer than 1 hour and 20 minutes. Top cooled cake with whipped topping when ready to serve.
Recipe Notes
Aluminum foil can be used to keep food moist, cook it evenly, and make clean-up easier.