Fuel Pressure, Lean mixture, pinging in Volvo 144 B20E

Dear All D-Jet experts. 
I have struggled for quite some time with a very lean mixture problem - lots of pinging from just a tad of throttle and lagging in rev-up. Based on all the wonderful input on this site I have tried to fix the issue my self - and now I need expert input please
But first - what have I ALREADY done to fix the issue;
- All Item numbers on the injection system checked and brought into conformance with original spec. Incl rebuilt fuelpump.
- Ignition - rebuilt original JFURX4 with contact free breaker - set at 10 deg BTDC without Vacc. it runs like a swiss clock 
- False air check with start-spray - no leaks
- Professionally Cleaned injectors installed
- Valve clearance adjusted to spec
- Cleaned fuel tank including new filters
- New fuel hoses and cleaned fuel lines
- Replaced the MAP sensor with another without change in condition
- New airfilter
- Cleaned and Adjusted Throttle switch
- Checked and cleaned all electrical connections to: MAP, Injectors, Temp sensors, Thermal time switch and fuel pump relay.
- Added a new 20mm2 ground cable direct on the intake manifold 
- Cleaned and closed the Damper valve on throttle clap.
- Checked AAV function
- New Valve cover vent hose installed
- New original Volvo B20E spark plugs 
- Runs only on 100 Octane fuel.

Still nothing changed - until I tried to squeeze the return fuel line with a pair of pliars - then suddenly the engine responded with a very healthy sound.
So I installed a Manometer and when I start cold - it shows 2.0 bars - after a few seconds it drops to 1,2 bar. I tried to increase the pressure on the Fuel Pressure regulator (I know Dr Djet strongly object to this indeed), but even if I screw it to the maximum setting, it would not go above 1,4 bar.
OK - so I bought a replacement - well it was "only" 120EUR used so I thought this was the final add to my endless list of fixes to get it running right. SAME #%#?!! result - and impossible to get over 1,6 bar even with the screw set at the maximum.

So - to the patient reader, here is the questions;
Could there perhaps be some old hardened fuel-residue stuck inside the FPR valve seat, and can it be cleaned out successfully with a chemical?
Is this a common issue, because the spring in the FPR gets weak over time, so adjustment becomes futile?
Can the membrane in the FPR not resist the modern Fuel with bio-alcohol additives so it leaks after some time?

Before I head out on the grey market and try another "Used & Tested" D-Jet FPR at a premium price - I would like to know if any other of you guys'n girls have solved a similar issue some other way?
Or - Is there an aftermarket alternative to the original, that is still on the market and that someone has successfully installed on a B20E engine?

Thank you for reading this - hope some one has time to nudge a fellow D-Jet owner, in the right direction with some good suggestions, BR Chris

 

Hi Chris,
at first you have to verify the pump gets enough fuel from the tank.

In most cases there are filters or similar devices inside the tank to prevent particles reaching the pump.
This could be clogged... by mud even old gasoline could have 'produced'.

No problem to find a new FPR that fits the car without any problems.
Here is one: www.ebay.de/itm/233812738789?_nkw=Webcon...tkp%3ABk9SR5b2yIC9ZA

www.ebay.de/itm/253916688146?_nkw=Malpas...tkp%3ABk9SR_Sk_4C9ZA
Regards
Norbert

Hi Chris,

welcome to Jetronic.org with your Volvo. I can assist your endless and expensive story with an ECU and a MAP sensor. But I am afraid that would only help my bank account not your engine.

Please put 12V on fuel pump to activate it and then disconnet return line after fuel pressure regulator and let this fuel run into a clean bucket.  It must be at least 750 cm³ / 30s  at a fuel pressure of 2 bar before pressure regulator. My suspicion is that it is too little delivery rate.

Dear Volker, thank you for your swift answer. When I replaced the unoriginal fuel pump with a original D-jet pump - I vented it through the cold start line and it delivered healthy amount of fuel. approx 1 dl in 4 sec. Plus - the fuel pressure peaks very high when I restrain the return line. So I would really like feedback on my questions about the old FPR´s, please. Some guy on youtube says that if the FPRs is left dry - they become leaky because the membrane dry out- is that true?
Thank you for taking the trouble with me - a true novice

Hi Chris,

sorry to disagree. When you measure delivery rate on CSV it is not against pressure regulator. It is speicified against 2.0 Bar pressure. That you can only measure behind pressure regulator.

Dear Volker, Got it now- the delivery volume must be from the return line
Will the pump be able to peak pressure up to 5 bar (because it can) when I restrain the return-line and still not be able to deliver the right volume?