My fuel injected, Kawi engined, 445 tractor gives off a strong smell of gasoline immediately after being shut off. I routinely throttle down just before turning it off so I assume it's not (normally) shooting excess fuel that's not burned in time, but that could be a wrong assumption. I don't see any visible gas leaks. The tractor starts, idles and runs as it should otherwise. Any ideas what could be causing this?