Pumpkin Burgers

1 1/2 pound lean ground beef
1 medium size onion, chopped
12 ounce jar chili sauce
1/2 cup pumpkin
1 teaspoon salt
1 teaspoon pepper
1 teaspoon pumpkin pie spice
1 can condensed tomato soup

Brown meat and onion. Add the other ingredients and simmer together for 1 hour. Serve on buns.