Classic case of o-ring-itis. Your turbo is just fine! (Breathe a sigh of relief.)
The fuel shutoff valve is located on top of the fuel injector pump. There is a black electrical wire connected to it. Remove the wire, then unscrew the valve with a suitable wrench. There should be a rubber o-ring on the end of the valve. (If not...well, there's your problem!) These o-rings gradually swell over time from contact with the fuel, and sometimes become displaced. If the o-ring appears to be undamaged, simply replace it in it's "slot" and re-install the valve. This should cure the problem. If it's damaged, you'll have to replace it. It shouldn't cost more than a few cents.
-mickey