Well....  no  :)

Back in ye olden days, when there were only two valves per cylinder, there
was a mechanical lift pump mounted on the back of the engine that sucked
fuel from the tank, and fed it up to the P7100 injection pump.  The P7100
was lubricated by engine oil, and if for some strange reason the mechanical
lift pump failed and stopped feeding fuel to the P7100, the extent of the
damage done was probably a sore toe from you kicking the truck because it
stopped running (not to mention all the fun of re-priming the fuel system
and getting it running again...  but still, no permanent damage done).

With the introduction of the 24V ISB engine, came electronics.  With that,
the mechanical lift pump was replaced with an electric pump, still mounted
on the left-rear of the engine, still sucking fuel from the fuel tank, but
now delivering it to a VP44 injection pump.  The VP44 no longer used engine
oil to lubricate itself as the P7100 did...  it relied on diesel fuel for
lubrication.  You can see where this is going....  when (not if, but when)
the electric lift pump failed, it starved the VP44 of fuel, which in very
short order would gawl itself all up, and you were then the proud owner of
TWO broken pumps....  one relatively cheap (the electric lift pump), and one
really expensive (the VP44).

The 3rd gen trucks, with their new ISBe (also called the HPCR, High-Pressure
Common Rail engine), use a different version of the same electric lift pump,
and a newer, higher-pressure, yet still fuel-lubricated CP3 pump.  The CP3
is cheaper to produce than the VP44, as there are no electronics (the VP44
contained electronics to control injection timing) - all the injection
timing is now done at the injectors themselves.  However, the CP3 is still
an expensive unit, and not something you want to fail (and believe me,
starve anything that spins around and around of lubrication, and that's
exactly what will happen).

Starting in model year '05, DC decided that pulling fuel 12 or so feet
through a tiny little tube probably wasn't the best use of a pump designed
to push, rather than pull - and re-re-re-designed the fuel system with an
in-tank "pusher" pump, that would now feed fuel directly to the CP3 (still
going through the stock fuel filter canister, however).  Guess what?
Sometimes, those pumps fail, too.  Of course, now you have the added fun of
dropping the tank, and removing the fuel module to replace the pump -
something that old 24V guys could do by feel on the side of the road on a
moonless night inside of 10 minutes.

Craig zip me an email so i can send you those pics.

kf4drr@windstream.net

All of what he says is correct - however, all that information is available
to any tech diagnosing the truck by simply hooking up the DRB3 will
operating the truck.  So having a rail pressure gauge is only going to be of
use to you to indicate that, "yep, there's a problem - better take it to the
dealer".  However, the truck having little to no power is going to be an
even bigger indicator of the same problem.

Okay - then that narrows things down a bit.  In your case, then, I'd say the
most important gauge is the tranny temp gauge, followed by the pyro,
followed by fuel pressure, and here's the reasoning:

In stock form, it's much more likely to kill your tranny from overheating it
(pulling heavy at slow speeds, no torque converter lock-up, building lots of
heat in the transmission) than it is to burn up your engine.  When towing
with my truck (and with the power dialed down to more sane levels), I could
see 230°F+ on my tranny temp, before I would hit 1300°F on the pyro.

Now, that doesn't mean that the engine is immune from melting itself...  the
3rd gens do run hotter than the previous 24V's, and with the right
combination of power and load, it's possible to see 1350°F+ on your pyro -
and that's not something you want to do for an extended period of time.  At
that point, it's time to slow down, downshift, get the engine RPMs (and
thereby boost) up to help cool those EGT's a bit.

And lastly, from our previous discussions, a failed/failing lift pump can
still cause damage to your injection pump...  not nearly as quickly as the
older 24V's, but the possibility is still there.

Other gauges - rail pressure, boost, and others, are simply
informational....  you're not going to kill your engine if you loose boost
(but you're going to know it right away, because power will be down, and
EGT's will be up).  You're also not going to damage anything if your FCA
breaks and you lose rail pressure.  Again, you're sure going to know it,
because power will be low-to-non-existant - but again, no damage can come of
it.

I'm not even going to venture a guess where ya plug that one in.
<VBG>

Roy