Yeah I've definitely done this. But sometimes even that hasn't worked.This reminds me of a crack that i had in on my furl tank. Fill up tanks, run for however long and then it dies. Bulb is flat. Re prime bulb and run again until it dies. I looked at everything and then i finally saw a small crack on the outside of the portable tank. That crack allowed air into the tank and the fuel line would lose pressure. I had to prime the bulb on a 12 mile run back to the ramp while my buddy drove my boat.
This is a really good idea. If the shop can't figure it out quickly, I'll try this on my own.I would try to run the boat off a different (known-good) portable tank and fuel line/bulb. That way you isolate the engine as much as possible.