Fueling Issues - Looking for opinions on PPR

[jwrayth]

Long time without posting. I took a bit of a DeLorean hiatus after 2 years of continued issues. The Summer 2019 issues with my car I've only had time to start looking at now, so was looking for some advice. The problems seem likely to be multiple issues, but manifested as low power, warm start issues, stalling on anything but gentle acceleration, no power above 15 mph.

Work done on the fuel system in advance of the problems;

• Fuel Pump replaced summer 2016, new in-tank filter screen and spring in pickup hose
  
• New fuel filter, fuel lines (amongst other VoD work) Christmas 2017
  
• No fueling issues summer 2018, but did have a sticky high idle
  
• Observed hot-start issues in Autumn 2018, Accumulator replaced December 2018 due to this
  

Work/tests done since investigating the issue

• New fuel pump fitted, as this was my initial suspect (2016 pump had gotten loud enough I could hear it in cabin)
  
• Fuel pump voltage tested (12v on the money)
  
• Hot-start o-rings replaced on PPR
  
• Car holds 42 PSI rest pressure for 1+ hour, so accumulator seems good.
  
• Fuel Pressure tested. 50 PSI control pressure, 59 PSI primary pressure
  

That last one led me to ordering some shims from the other club. I started with the smallest and worked my way up but was noticing zero impact until I had added 1.25mm of shims, at which point suddenly my primary and control pressure were reading the same, and went up to 70 psi (I stopped the test as it shot up suddenly, so I could release pressure via the drain valve).

So I've returned the PPR to it's original state other than the replaced o-rings and I'm getting the original values on my pressure tests again.

I've done some reading of the various forums (DeLorean and otherwise) and not found someone experiencing this issue so I thought I'd put it up for some collective input before I proceed. The shims having no impact on the pressure makes me think I'm not getting enough fuel to the distributor itself...

[Chris P]

Is your car Turbo-charged?

[jwrayth]

Nope. Stock PRV, lambda system and all. Has the UK Stainless Steel exhaust on it but I don't imagine that would make a difference.

Oh, and the fuel pump setup is the OEM style not the modern one-piece unit.

[Rissy]

When you put the fuel pump assembly back in the tank, did you make sure, for SURE, that you didn't twist or kink either of the fuel hoses?

[Chris P]

did you fit a spring thingy in the inlet pick up pipe?

[jwrayth]

@ChrisM - I'm 99% sure, but I'm going into the tank anyway to check. Need to use up the 20 litres I've already drained so I have capacity to drain the rest Will report back once I'm in proper and can inspect all the gubbins without submersing my arm.

@ChrisP - Yes, it has. I had the traditional pipe-collpasing problem in summer 2016 and replaced the pickup hose then along with adding the spring to it.

I should mention as well that in 2017 VoD work I had my injectors cleaned and tested too.

[Rissy]

(27 Jan 2020, 09:02)jwrayth Wrote: Need to use up the 20 litres I've already drained so I have capacity to drain the rest Will report back once I'm in proper and can inspect all the gubbins without submersing my arm.

Although i've now put it back in, just the other week there, I had my tank out of the chassis completely. I had the same issue. A LOT of fuel in there (30ltrs). I just drained the fuel into my two small 5ltr fuel tanks and bought an additional 20ltr Jerry Can from Halfords. Arguably spending near enough the same money on the Jerry Can as the cost the fuel I was saving, but i'm without a doubt i'll use it again. So yeah, I'm now my own little petrol station at home. Something to think about rather than "using it up" just for the sake of it...

Just to check. By "PPR" you mean the fuel regulator/distributor? (I hate acronyms, because they mean different things to different people, and without clarification in the first use of it....)

[jwrayth]

(27 Jan 2020, 09:31)Rissy Wrote: So yeah, I'm now my own little petrol station at home.  Something to think about rather than "using it up" just for the sake of it...

The daily driver does enough milage I can just fill her up with it this week instead of a trip to the pumps Plus since the DeLorean has effectively been sitting since August I'd want some fresh fuel in her once I get all the other problems figured out!

(27 Jan 2020, 09:31)Rissy Wrote: Just to check.  By "PPR" you mean the fuel regulator/distributor? (I hate acronyms, because they mean different things to different people, and without clarification in the first use of it....)

Yes, to be clear I'm talking about the primary pressure regulator of the fuel distributor. Added a link to rule out any confusion

[Chris Williams]

Quote:That last one led me to ordering some shims from the other club. I started with the smallest and worked my way up but was noticing zero impact until I had added 1.25mm of shims, at which point suddenly my primary and control pressure were reading the same, and went up to 70 psi (I stopped the test as it shot up suddenly, so I could release pressure via the drain valve)

The 'shim' thing IMHO is a total red herring. If it were me I would try swapping the metering head with a known good one.
Chris

[jwrayth]

I have a spare fuel distributor, but "known good one" is a stretch. It came from a running Volvo 760 with the PRV6, but I've had it sitting bagged up in my parts bin for some time. I could look at swapping that on but that seems like shotgun debugging. Might just have to pony up the money for a refurb...

[Chris Williams]

Quote:I could look at swapping that on but that seems like shotgun debugging

IF you have that option it's often the easiest way, Whilst others may disagree the whole fuel pressure thing is IMHO a waste of time. They will run very well with a variation of pressure SO long as everything else is correct. 
Chris

[jwrayth]

I follow that thinking too. The fuel pressure is so far below the min spec in the manual that it seems to be the issue and my symptoms match that, but the odd behavior with the shims/PPR is what leads my thinking at to there either being a problem in the tank or internal to the fuel distributor.

[jwrayth]

Been into the fuel tank and nothing was kinked or rotten. I'm renewing the grommet that sits between the baffle and the pickup hose as I tore the existing one removing it all from the tank, but otherwise I don't have a whole lot to show from going into the tank.

Once I've got it plumbed back together I think the distributor is the isolated cause (for the fuel pressure issues at least).

[Rissy]

Have you tested the full range of flow of fuel from each of the injectors?

[jwrayth]

Not myself but in 2017 I had my injectors tested and cleaned along with some spares I had. All came back within spec, but the 6 best ones had been marked for me as part of the testing so I installed those.

Once I've got the in-tank bits re-installed and some fresh fuel I'll pop the injectors out and give them a check too though