Mix together flour, salt, baking soda, baking powder, allspice and nutmeg. In a large bowl, beat together vegetable oil, brown sugar, eggs, orange juice and pumpkin. Stir flour mixture into pumpkin mixture until just combined. Pour batter into prepared loaf pan.
Bake in preheated oven for 50 to 60 minutes, until a toothpick inserted into center of the loaf comes out clean.