Experienced mechanic but can't figure this one out, 15 hp evinrude with new tank,hose and ball and everything double clamped. Anyhow the ball pumps up good and the motor runs good but after about 5 mins at full throttle the ball will suck it's self empty and the motor dies. I can pump the ball every now and then and it continues as normal. The motor is a 89 evinrude that I also put a new fuel and water pump in and a inline fuel filter, also cleaned carb several times but nothing ever there as far as dirt