In medium bowl, whisk together ketchup, molasses, mustard, and black pepper.
In the Instant Pot using the sauté function, cook bacon, onion, and bell pepper, uncovered, for 6 minutes, or until bacon crisps. Hit cancel to turn off sauté function. Pour off any excess fat.
Stir in beans. Spoon ketchup mixture on top; do not stir. Cover and lock lid. Select Manual/Pressure Cook and cook at high pressure for 8 minutes.
Once cooking is complete, release pressure by using natural release function. Stir in vinegar and let stand at least 5 minutes for flavors to absorb.