The closest I've had to that is a bad fuel pressure regulator in my old car. The diaphragm ruptured, causing gas to go into the manifold via a pressure sensing line. I had to start the car as if it was flooded (because it was). The leak was small enough it didn't bother things once the engine was running.
But I'm sure there's probably a few things that can cause that.
But I'm sure there's probably a few things that can cause that.