Primer bulb on fuel system will not stay hard (primed). In the process of changing out all hoses from tank to the motor. Any suggestions on how to narrow my issue down between the fuel line system or the fuel pump. The motor runs good initially when first started, but after throttling back after a long run it takes several start attempts to get the motor to pick up fuel. It will finally pick up and run full throttle again. Any and all suggestions appreciated to fix my fuel issues.