Working on my daughters 1991 Glastron, 4.3 Mercruiser, mercruiser 2 bbl, W/ Alpha 1 drive. The carb is making a very loud whistling noise which is comming from a port on the top left of the carb, if I put my finger over the port it kills the engine. Also this carb does not have a choke flap on it. The carb was replaced by by a local marina a couple of weeks ago. Any ideas?? Thanks Oh, the boat was put in the shop because it was flooding at idle. After they rebuilt the carb they called and said the carb was bad as it would not get fuel now so it would have to be replaced?? Any ideas? Thanks