Mix 2 cups all-purpose flour, 2 tsp baking powder, 2 tsp ground cinnamon, 1 tsp baking soda and ¼ tsp salt in a large mixing bowl and keep aside.
In a separate mixing bowl, mix pumpkin, sugar, oil and eggs and beat this mixture at a low speed until combined.
Now beat in the flour mixture until just combined.
Pour this mixture in 15 by 10 greased pan.
Now bake this batter for 25-30 minutes in a preheated pan at 350 F or until the toothpick inserted at the center of the cake comes out clean.
Now cool it completely for about 45 minutes.