Preheat oven to 350 degrees F. Lightly grease 2 8″x4″ loaf pans.
In a large bowl, beat margarine and sugar together until light and fluffy.
Stir in eggs, banana, and pineapple.
In a separate bowl, sift together flour, baking soda, baking powder and salt.
Stir flour mixture into egg mixture.
Fold in coconut and walnuts.
Pour batter into prepared loaf pans and cover with foil.
Bake for 45 minutes.
Remove foil and bake an additional 15 minutes, or until a toothpick inserted into center of the loaf comes out clean.