WHISK flour, baking powder, baking soda, pumpkin pie spice, salt and sugar in a large bowl. Whisk in buttermilk, pumpkin, eggs, oil and vanilla until well blended. SPRAY a large nonstick griddle or skillet with no-stick cooking spray. Heat over medium heat. POUR batter by scant 1/3 cupfuls into skillet, working in batches. Cook until bubbles form on surface of pancakes and bottoms are lightly browned, about 1 1/2 minutes per side. Repeat with remaining batter, spraying skillet with no-stick cooking spray between batches as needed. SERVE warm with syrup.