CRD Not Starting - Injector Issues?

[besp]

Evening fella's.

2008 3.0L Common Rail

1000km ago it started taking a half second longer cranking to start (put it down to the new battery being a lower cold crank capacity).
400km ago the truck started kicking out a bit of black smoke (not just the usual from a heavy right foot) possibly a bit worse over the 200km journey.
Next day another 200km but this time with the black smoke heavier (not clouds of it, just a constant under load) and this time i felt a general loss of power over the trip, a few hesitations when accelerating and once I got to camp it wouldn't start again.

It cranks but just wont start. Only getting 1600psi (110bar) at the rail. Understand I need about 4000psi (275bar) at cranking.
Fuel is exiting the rail to return line. Not just a few drips but a stream.
Replaced the filter. Had a few air bleed issues but now sorted.
Replaced the rail relief valve. Still only 1600psi.
Popped the banjo bolt off the rail and confirmed fuel from injector spill line and nothing from the relief valve.
Popped the spill lines off the injectors and cylinders 2 & 4 are leaking back.
Checked sensor, pump and injector electrics for opens/shorts/voltages/resistances etc as per the workshop manual.

I have ordered some injectors but want to be as sure as possible before I fit them as they are not cheap. Really, really, not cheap.

So, questions:
1) Do the symptoms described suggest the injectors are the likely culprit?
2) Is the leak back likely to cause this pressure drop at the rail? Have you seen similar numbers?

All ideas welcome as currently stuck in a caravan park!

Thanks.

[besp]

Oh and on the last drive I got a P1089 (low fuel pump pressure)
Whilst troubleshooting I also got P0193 (fuel rail pressure sensor circuit high input) but I think that was just from when I pulled the sensor plug!

[happygu]

It could be a leaking injector, as it either has to be the pressure relief valve or an injector, for the rail pressure not to come up to spec. I guess it could also be a worn pump, but that would be less likely - just going by known troubles, and I would think the pump failing would be more gradual.

It is most likely only one (or two) injectors, rather than the all four, so you could try one at a time to save some cash.

[happygu]

Just checked mine for you, and when turning the key to glow - the pressure still remains low, but when I turn the key to start, it immediately goes to around 5000 PSI

[besp]

Thanks HappyGU. Especially for going outside!
Sounds like you think I'm on the right track.
Only two seem to be leaking back a lot. I have ordered 4 as I guess the others will be on their way too after 220k km's?

[mudski]

Dont forget you should be replacing the injector lines too. As this is recommended by Nissan to do so. I am led to believe the reasoning is where the pipe seals against the injector is a soft material and there for they wont seal as good the second time around due to the very high pressures.

[threedogs]

Can I suggest you by a Scan-gauge for your CRD, best bit of kit you can Buy.
you'll be able to remove any errors as well. money well spent IMO.
Is your intercooler oily???

[besp]

Thanks for the replies.

Mudski - Yep they are in the a workshop
a manual as a must replace. Several injection specialists I've spoken to say they should be ok to reuse if I'm careful not to damage the ends, but replace at the first sign of a leak. I'm happy with that approach as they are $70 a go and a week away!!

Threedogs - I have an EDS (Engine Data Scan) which is a copy of a scanguage. I have this mounted on the instrument console. I also use an app called Torque which Iuse when I need more info or to log and graph. That's how I got my rail pressures. Great bits of kit.
I have no oil in the intercooler. Already have a catch can. I really should get some info in a signature!

[besp]

I replaced the injectors today. Truck started up after a couple of long cranks and chucked out a ton of white smoke. It registered about 12000psi max. Didn't rev it or do anymore today as it was getting dark and a bit antisocial to smoke out the caravan park at tea time!

I checked my glow plugs today as well (I only checked they were getting power to the rail before).
Cylinders 2 and 4 with the buggered injectors had good glow plugs.
Cylinders 1 and 3 with the good(ish) injectors had buggered plugs.
Coincidence?

[mudski]

Well change them and see what happens.