Model Mer/Mar 8/9.9 (4-stroke) Ser# begins 0H004. Motor starts easily and idles smoothly. Pumps water very well. Put it in gear and it takes right off and runs well for a couple minutes, then just dies. Wait a few minutes and it will restart and run good for a bit and then do the same thing. I first thought it was running out of fuel, but the pump ball in the fuel line remains firm. It will die even as I keep the ball as firm as possible. Where should I began? All connections on the lines between the tank and carb are good. Could a bad fuel pump cause this even as I manually keep the line full? Thanks for any suggestions!