PLACE beans in large heavy saucepan. Add enough water to cover. Bring to boil. Cook on medium-low heat 2-1/2 hours or until beans are tender.
COOK bacon in large skillet on medium heat just until crispy, turning frequently. Drain on paper towels, reserving drippings in skillet; crumble bacon.
ADD bacon, corn, sausage and onion to beans in saucepan. Reduce heat to low; simmer 1 hour.
STIR flour into reserved bacon drippings in skillet. Cook on medium-low heat until bubbly, stirring frequently. Gradually stir in 1-1/2 cups water until well blended. Cook on medium heat until mixture boils and thickens, stirring constantly. Add to soup; simmer 30 minutes. Season to taste with pepper.