Ok, I have just finished going through a 1996 Mercury sport jet 120 (Force 120 power head) that had sat for three years. I put it in the water, it started within 6 seconds and i let it idle for about 15 minutes to let everything circulate and the temperature to stabilize. It was running like new. I was using an external fuel tank so I know the fuel was clean. I slowly powered up and it took off strong. I ran it about 5 minutes and I slowly powered back to idle when it died. I couldn't get it started again. I found fuel puddled in the bottom of the attenuator box. The top cylinder was pressurized when I removed the plug. The compression on all cylinders are all around 120 psi. I checked the carb floats and enricher resistance. I now suspect the reed valve assembly. Does this sound like a reed valve problem?