Yes. If you're in neutral you should be prohibited from raising the fuel rail pressure to maximum - under no load, the engine should rev quite freely without a lot of fuel input. Pouring 30,000psi into a CR diesel that's in neutral should understandably result in a LOT of wasted fuel and potentially over-running the governor. If the RPM climbs too high, there's every chance fuel will continue to burn well into the exhaust stroke.
Introducing that much fuel into the exhaust stroke is not only wasteful but it'll rev the ringer out of your turbocharger as well. Imagine not only having the turbo at full boost, but dumping loads of fuel into a chamber that's venting straight into the exhaust ... watch the turbocharger fail. EGTs will skyrocket well past the capacity of the alloy head to manage, and that engine will stop. Forever.
There's also a good chance that with that much fuel available and combustion happening at very high rates, the amount of bypass will be extremely large and, upon vaporising the sump oil, will cause overrun - where the governor no longer works, and the engine RPM climbs uncontrollably (without fuel) until the engine self-destructs. Once a diesel starts overrunning, you can't shut it down unless you can either disconnect the PCV from the intake, or stop the engine from breathing fresh air (block the intake). Using your hand to do that is NOT recommended, it can tear your skin off!
Granted these are worst-case scenarios, but that's what the limiter is designed to prevent.
Here's some interesting reading -
Engine Overspeed and
Diesel Engine Runaway.
Here's a couple of interesting Youtube vids.
[YT]https://www.youtube.com/watch?v=3NRaqgab0_w[/YT]
[YT]https://www.youtube.com/watch?v=rLzf3ItkbOE[/YT]
