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.

This is the justification from the mechanic I have been dealing with
after asking him why a rail pressure gauge is preferred over the fuel
pressure:

"On the rail pressure, low or fluctuating rail pressure don't
necessarily equate to a dead CP3 (injection pump).  It's use is to give
the operator a base line of rail operating pressures at given load and
engine rpm's.  Out of the norm for same driving conditions could help
diagnose the concern with the high pressure side of the fuel system.
Ie. the fuel control acuator (fca) sticking or cycling improperly (low
to no rail pressure) or a bad rail pressure sensor or fuel valve. both
would cause performance concerns and could asst. Dodge or other diesel
techs in more accurate diagnosis of the concern.  For example the CP3
could be failing causing a low rail pressure, if the tech, did
troubleshooting and found the FCA, rail sensors and low pressure side
volume's to be up to par, the ECM (engine control module)  or CP3 would
be the obvious culprit."

Note, I am not trying to pit anyone against anyone.  I trust this guy,
he's a great mechanic.  What I am trying to overcome is my own personal
ignorance on the matter.  I'd like to understand better why one is
better than the other.  Or ... if I'd be better served with scrapping
the fuel gauges altogether and just put in two gauges (tranny temp and
pyro).

This is what I am trying to avoid.  Having a gauge for the sake of
having a gauge doesn't excite me at all.

I highly doubt that my truck will ever be anything but stock.  I like it
just the way it is.

Okay ... you *might* need to calm down a little.   :-)

Craig C.

First, while it's true the 3rd gen trucks' lift pumps were more reliable
than previous years, and the CP3 pump is much more tolerant of lower fuel
pressures, DC felt that the lift pump was still enough of an issue that they
re-designed the low-pressure side of the fuel system, and re-located the
fuel pump inside the tank.

There have still been reports of lift pumps failing, even on the 3rd gen
trucks.  While this doesn't automatically trash the injection pump like it
used to in the VP44 days, it's still not a good thing for the CP3.  Yes, the
CP3 has it's own small gerotor lift pump built in, which in other
applications draws straight from a fuel source (no aux. lift pump), but
that's just it - it's not trying to suck fuel through a locked-up electric
lift pump in those applications.

IMO, a fuel pressure gauge is still useful.  I use mine all the time to
judge when it's time to change fuel filters (I notice the drop-off in
pressure, meaning the filter's getting more loaded up with gunk).

A rail pressure gauge is really just a "gee-whiz" kind of gauge, unless
you're planning on playing around with your fuel pressure to get more power
out of the engine.  That's a whole 'nother story, then - and in that case,
yes, a rail pressure gauge could be useful.  I, personally, am against
cranking up fuel pressure much beyond stock (the pictures I've seen of worn
injectors sold me on that one).  I currently have an Edge EZ box hooked up,
that I run on level 1 (mildest setting), just to give a little more fuel way
down low.

As for the boost gauge, again - not all that useful if you're running a
stock truck.  It can be helpful in diagnosing problems (for instance, a
blown, or even leaking,  intercooler boot is going to be easily noticable on
your boost gauge).

For reference, I currently run 7 gauges - pre-and-post-turbo EGT's
(pre-turbo being read by my TST box), boost, fuel pressure, tranny temp, oil
pressure, and water temp (needed to fill the last hole, and I never trust
the factory idiot lights in the shape of gauges).

Need a second opinion:

I am having Pricol Optix gauges installed on my 2004 Ram, CTD in the
next few weeks.  I like the Optix gauges because they match the OEM dash.

http://www.danininc.com/opticdetail22.html

Mounting will be a 3 pod dash mount.  I want a tranny temp, pyro and I
thought a fuel pressure gauge.  However, the guy doing the install feels
that I would be better served with a rail pressure gauge since the pump
issue in my model Ram is no longer an issue at all.

Would like opinions ...

I thought about a boost gauge, but can't really think of what that gauge
gives me that I can't tell without it.

TIA.
Craig C.