Hoping to get my 2008 mj rail figures tonight
I am impressed you got it apart,
and a little confused by your "improved pressure"
...Well the thing is that I haven't got it apart! I'm still trying to figure out a way/improvise a tool to remove and refit the inlet pipe! The filter in the photograph is the brand-new one which awaits fitting. - There just to show how small it is. The original one is still in there!
On this particular version of the pump the filter is directly behind the inlet and so (for the purposes of flushing to some degree) 'accessible' with the long thin swabs that I used. Those swabs are designed to get right to the back of the human nasal cavity and swoosh around - the walls of a straight cylinder are no challenge to them; and they're actually quite close in size to the internal bore. - Almost like a miniature bottle brush!
Basically - the inside of the original strainer has had a wipe down with an oily rag and a slunge out with clean diesel; a bit like sticking a tall glass under a running tap and wiping the insides with a dish brush; not the idea way of washing up, but it would have an effect. - Most of what I managed to loosen with the swab would have went back out the way it came in.
As for the pressure... Well when they start to teach you electronics/electrics they draw attention to water/fluid analogies. That's because when electricity was discovered this was the first thing the scientists of the day latched on to; And in fact you'll find that many of the formulae used in 'electrics Vs hydraulics' are directly translatable...
Rail pressure - on at least some models of the CP1 family - is controlled and modulated by a solenoid valve which works on the
inlet side...
There are variations (and this might be one of them) that work the other way around; i.e. by bleeding off pressure. - However the point is that output pressure
can be modulated by restricting the
'current flowing' into the pump.
As a paradigm, think of an LED which has very low internal resistance. Apply a voltage across it and, unless that voltage is very low and controlled (so that limited current flows anyway), the device will quickly cook itself - so we fit a resistor in series with it to limit
the current. A restriction in a fluid pipe will have much the same effect.
Often in fault-finding (generally; with anything) it's useful to consider the history of the fault and mode(s) of failure...
In this case, directly after the 'thaw' and replacement of the 'killed' lift pump, the car would barely start, idle or rev. Winter diesel along with injector cleaner was added which
didn't immediately improve things; it was only after the car had been left with this mix 'soaking' in the system for a couple of days, that things cleared enough for it to start relatively easily and rev relatively freely.
At that stage pressure readings seemed 'in the ballpark'; though the (expected) very high pressure readings (over 1000 Bar) were never seen. When the car was test-driven it effectively cut out under load and when ascending hills... Hindsight being 20:20, I should maybe have joined the dots at that point. But then the information which joins them has only just become available;
The Ducato thread and associated 'rabbit hole' was only discovered the other night while looking for something else. The same goes for the exploded diagram specific to the model of CP1H3 (there seem to be many variants) that I have.
The videos that thread leads you to, all seem to be in foreign language with 'AI' (Actually Imbecilic!) translations that amount to complete and utter gibberish. - It's not remotely clear (for example) on what side of the LP pump (feed or return) they're measuring pressure. And in that particular context it's probably important they make that test, because their pumps are relatively inaccessible. - Nor is it clear whether
on those pumps, the strainer is placed on the feed or return side!
The thing is though - the symptoms experienced by the Ducato owners are quite relatable. And let's not forget, we have two 'Qubo/Fiorino' examples here, Steve's and my own.
...So back to that 'series resistor'. In a simple LED circuit that is put there as a
current limiting device; i.e. it allows relatively low current to pass.
What I suggest I've seen is that the partially-blocked strainer has acted as a
current (flow)
limiter such that enough 'current' may flow to allow relatively acceptable pressures to be achieved at low/no load. Ultimately though when high demand was signalled - such as during the test drive, or other other night when I 'briefly floored' the accelerator in an attempt to replicated Mike's results - the engine simply died.
In fact - that incident was interesting (hindsight again) because the engine simply cut and threw up the MIL/P0089 when the accelerator was floored - it didn't even get as far as revving...
The
supply 'current' (fuel flow) being
limited by the 'resistance' imposed by a partially blocked inlet strainer; which would have much the same effect as an FPR working on the inlet side. Purely theory of course at this stage. But consider too the consistent P0089 message;
fuel pressure regulator performance. The ECU would have no way of 'knowing' that it was the blocked strainer which was restricting the inlet... when it 'called' for the FPR to deliver maximum pressure and it failed to do so; it simply did what it was meant to do.
There is much more checking and testing to be done (I only had a few minutes yesterday) before anything can really be 'called' on this; the pressures I'm seeing now at relatively low revs aren't entirely inconsistent with what went before; it's the fact that I'm now seeing those 'six figure' numbers at higher revs where they were absent before.
Hope that clarifies things a bit. And thanks for offering to gather those pressure figures. - It would be particularly interesting to hear if you see those very high figures when you 'blip' the throttle and if they seem to fall away once the engine 'realises' it's not under load.
you could run one of those 'zero point energy/perpetual motion machines off of that! 
