Preheat oven to 325. In large dutch oven or deep pan heat baked beans on low.
In large skillet cook chopped bacon until almost done. Remove bacon from pan and set aside. Save bacon drippings in small bowl. In same pan add chopped onion and cook on low until onion is soft but not crispy. Remove onion and mix with bacon. set aside.
In same pan add 1 tablespoon of baking drippings. Drain and add pineapple tidbits and heat on low. Add black strap mollasses, stir and heat through. If needed add a little bit more of the bacon drippings to keep pineapple from drying out. Stir in 1/2 the bread crumbs and heat on low.
Remove pineapple mixture from heat. Pour baked beans into a baking dish. Mix pineapple mixture to beans. Mix into the beans 1/2 the bacon and onions. Add remaining bread crumbs to beans and stir. Sprinkle remaining bacon and onions on top of beans. Sprinkle brown sugar on top. Heat in 325 degree oven for 30 minutes.