Preheat oven to 350 degrees F (175 degrees C). Grease one 9 x 5 inch loaf pan.
In a large bowl, cream shortening and sugar together. Mix in eggs. Add zucchini, water, and vanilla; stir. Blend in flour, baking soda, salt , baking powder, and pumpkin pie spice. Stir in nuts.
Divide batter in half, and add cocoa powder and chocolate chips to one of the halves. Pour plain batter into bottom of the loaf pan. Pour chocolate batter on top of plain batter.
Bake until wooden pick inserted into center comes out clean, about 1 hour. Cool 10 minutes, and remove from pan. Store in refrigerator.