Preheat oven to 350°F and prepare a loaf pan with nonstick spray or parchment.
In a small bowl, mix together flour and spices. In a larger bowl, beat together pumpkin, oil, sugar, and eggs. Add flour mixture, a little at a time, until just mixed. Stir in persimmons.
Chop the walnuts and reserve about 1/4. Fold 3/4 of the walnuts into the batter.
Pour batter in the prepared pan and scatter the remaining walnut pieces on top.
Bake for about 60 minutes, or until a toothpick inserted in the center comes out clean.
Notes
To line the pan, I like to use baking paper laid across in two perpendicular strips, as it doesn't require extra oil and makes cleanup easy.