D5 won't start

[BobXC]

Hi
I'm new to XC90 ownership and this forum, so please bear with.
Just acquired a non-running 2009 XC90 with D5 grey top engine. The engine fires and runs to about 1200 rpm, then stops after 1-2 seconds. This is consistent behaviour.
I've done the obvious, like renewing the fuel filter, testing injector flowback, checked plenty of fuel is arriving at the injector pump, even replaced the pump with a know good one.
When my VIDA/DICE was running, it showed good consistent fuel pressure up to the point of stopping, when it tailed off. (VIDA has now stopped communicating, so I can't give any fault codes yet until I fix that.)
It looks as though everything is good to go, but once running some parameter must be out of range so the engine control shuts it down.
Can anyone point me to a detailed technical description of the start-up process - i.e. the order things are done and checked? I'd like to understand the process to help with diagnosis and interpreting the fault codes.
Thanks in advance.

[Bonefishblues]

In-tank fuel pump? Sounds a bit like an issue I had with mine where carp was getting sucked into the pump and bringing me to a halt, which then cleared when stopped and so on. Suspect not, but just to throw it in.

[SwissXC90]

A carp would definitely be a problem, that can be a big fish

[Tannaton]

....could be worse, could be a turbot getting in there.

Anyhow... if you have monitored the fuel pressure and it tails off - you next need to determine if that was commanded and you do that by looking at the fuel pressure regulator duty cycle (I think....)

If it is not commanded, or you can't get VIDA up and running then I would do a leak back test on the injectors, if one is faulty and excessively leaking back this will cause fuel pressure to drop. However injectors usually leak back consistently and prevent an engine starting if they were that leaky, but it's still something to eliminate.

Plenty of vids on YouTube, can be done just as well with drinks bottles but kits available on ebay for £10-£20. If buying a kit remember you have 5 cylinders...

[BobXC]

I've checked the fuel system is free of fish, and also done the leak back test - no problem there.
As you mentioned, I don't know whether it stops because the fuel pressure falls, or it falls because it is told to stop. My guess is the latter.
That's why I need to understand the whole process, and the possible reasons for shutting things down.

[Moose Test]

I'm not an expert but from an ideological stand point, and I'm really chucking this out there as a point to consider rather than claiming deep and arcane knowledge but; I'm dubious that the Volvo engine management system is Full Authority to the degree that it can shut the engine down completely once it has started. We could consider that it is sufficiently confident you're not driving down the motorway at speed, since it can measure wheel speed, transmission speed etc. But it can't know that you haven't just stalled across a railway line and there's an oncoming train bearing down on you. That's why the variously named "limp" and "reduced performance" modes exist.

And my first point not withstanding, given that the activation of reduced performance modes is always greeted by the appearance of the yellow/red master caution light and a DIM text message, if something so serious had occurred that the ECM had decided to shut the engine down completely, I'd be pretty certain there would be warnings on the dash for this too, not to mention DTCs stored.

Which brings me to my last point, is the problem with your VIDA/DICE setup between the laptop/pc/tablet and DICE, or is it that DICE can no longer communicate with the vehicle? If you determine it to be the latter, then I'd be inclined to suggest that it is not a coincidence.

[cheshired5]

Originally Posted by BobXC

Can anyone point me to a detailed technical description of the start-up process - i.e. the order things are done and checked?

Pretty sure the flow chart or similar for that is all covered in Vida.
The car doesn't need to be connected, just enter the chassis number or select the car from the Vehicle Profile screen if it's connected previously then browse the Design and Function section in the Information >Repair tabs

It will give the principles for all of the major functions and processes on the car.

[BobXC]

Many thanks cheshired5. I'll take a look.

[BobXC]

Sometimes it's just the simplest things. I noticed some discussion about white smoke or black smoke, so thought this should be checked. Result - NO smoke! Nothing coming out of the tailpipe at all. So broke the joint between DPF and CAT, and it now runs! Maybe the DPF needs a bit of a clean, or disposal.

[Bonefishblues]

Full of fish, no doubt.