Preheat oven to 350 degrees F (175 degrees C).Grease and flour a 9x13 inch pan.
In a large bowl, stir together the cake mix and instant pudding. Add the water, oil and eggs, mix until smooth and well blended. Spread batter evenly into the prepared pan.
Bake for 40 to45 minutes in the preheated oven, until a toothpick inserted comes out clean. While the cake is still hot, poke holes in the top with a fork. In a small bowl, mix together the lemon juice and confectioners sugar until smooth. Pour over hot cake.