Re: 1991 5.7 350 Inboard fuel issues........
If this is a recent problem and not one you've had all allong I suspect trash in your fuel lines, maybe in your tank and lines pre filter. If posiible, I would disconnect your fuel lines from the tank, filters, and engine and blow them out with low pressure air. Change or clean your fuel filter as well. If it is starting fine and running well but runs the carb out of gas it's probibly an obstruction in the tank/lines or stuck bowl float, or fuel pump. It almost sounds like it draws gas fine than picks something up that blocks the line, perhaps a chunk of crud in the tank that is sucked up and block the pick up but falls back when engine dies and vaccum is let off. I would blow the lines before next use to eliminate that possibility, take a small hammer or something you can tap on the carb bowl with when it starts to run out of gas, allot of times that will un-stick a stuck float. If those don't pinpoint the problem than i'd look to fuel pumps and the tank itself. Something I learned in the Navy, allways check the simple solutions first as they are less expensive and less manhour intensive, and ALWAYS expect Murphy to show up so take steps to make your work bulletproof. Hope this helps ya.
Art
