I have a 2006 115 Merc that I am having fuel pressure problems with. It will start and has a fuel pressure of 35 pounds while in idle at 3000 rpm or 40 pounds when under power at 3000 rpm and will maintain that for about 10 minutes. Then the fuel presure starts to drop slowly until the rpms begin to decline and finally the engine dies. If I wait for about 15 minutes, I can then start the engine again and it will do the same thing. Any idea why this is happening?