In a saucepan, cook potatoes in boiling salted water until tender.
Meanwhile, cut sausage into 1/2-in. slices; saute in a skillet until browned. Drain and place in a large bowl. Drain potatoes; peel and cut into 3/4-in. cubes. Add sausage; keep warm.
Cook bacon until crisp; crumble and set aside. Drain all but 3 tablespoons of drippings; saute onion in drippings until tender. Stir in the flour, salt, celery seed and pepper; blend well. Add sugar, water and vinegar; bring to a boil. Boil for 2 minutes.
Pour over potato mixture and stir gently to coat. Sprinkle with bacon. Serve warm. Yield: 12-14 servings.