The 92 series engines don't typically come equipped with emergency shutdown. The E-stop, as it was called, pretty much became unnecessary with the advent of the spring loaded rack control tube. The old style tube would allow one stuck injector to lock all the racks in full fuel and cause a runaway engine. But the updated tube isolates each injector rack from all the others. About the only reason a 92 would runaway would be because of an internal fuel leak that wasn't detected because no one ever checked the oil.
If the blower bypass valve were to stick open, the engine would be very hard to start or not start at all.
Black smoke at full throttle could be caused by any number of things. The first place to look is the air intake and filtration system. The engine must get enough air to completely burn all the fuel and a clogged or damaged intake will not allow enough flow. The same goes for the exhaust system. If the exhaust is clogged, damaged or improperly routed, then the engine cannot breathe and smoking and performance issues will result.
A poorly functioning or damaged turbocharger will also starve the engine for air and incomplete combustion with black smoke will occur. Sometimes a visual inspection of the turbo will reveal an obvious problem but sometimes it requires that "boost" or turbo pressure be measured with a gauge.
Over fueling will also cause an engine to smoke black. This can be from malfunctioning or mis-timed injectors, a governor that is out of adjustment or from incorrect injectors being installed.
Or, it could be a combination of two or more of these things. A step by step inspection and evaluation is needed to identify the reason and it usually takes a well versed, experienced Detroit wrench to keep these babies up to snuff.
I see that yours is aftercooled and that can be a source of concern if the cooler fins get oiled from a leaking blower shaft seal and get clogged with crud.
I wish you good fortune getting it figured out. A good Detroit mechanic is a good friend to have around the boat.
