A customer launched his boat this spring without all of the cooling hoses attached and seriously overheated his engine. Fried his raw water pump and fiberglass muffler ($!!) Marine mechanical fuel pumps have a tube that runs to the carb that route any fuel that passes through a bad pump diaphragm. There was fuel in the sight tube and I disassembled the pump to find a deteriorated diaphragm, possibly from the overheating. I noticed the grip coating on the Fram filter was blistered. This motor must have gotten amazingly hot.