I am getting air bubbles in the fuel line, which have caused it stop running. The dealer thinks the fuel pump in the tank is the problem. The bubbles can be seen in the clear plastic line from the fuel filter to the engine. They replaced the fuel filter but are still getting air in the line. They have also inspected the fuel line from the tank to the filter and found no leaks. I have a 2003 158" and bought it new. Any thoughts?