I have a old evinrude 6hp motor that I am having an issue with. The fuel wont stay primed. I have replaced all the fuel lines and all the fittings and bulb to the gas tank. I have also removed the fuel feed tube in the tank to make sure it wasent leaking air into the system somehow. I put a clear fuel line from the fuel filter to the carb and I can get the motor to start and then air seems to be getting in the line from the carb end. I am not sure how this is happening or how to fix it. I am an electrican if this was a spark problem it would me much easier for me. Any thoughs of what to try would be greatly appreaciated.