I was using my tractor this weekend when I smelt a strong oder of diesel. I got off and start looking and most of the right side of the motor was covered in fuel. I found fuel leaking from the center injector up from where the body of the injector threads in. The fuel line felt tight and so did the injector. Strange thing there is no fuel cut off valve that I could see, it stopped leaking when the tank was empty. Any ideas?