fuel pressure loss?

[AK83]

Hey brains trust.
Hoping someone out there can guide my nephew(via me) to help diagnose why he's having trouble starting his soon be on the road TD5.

First up, he bought the TD5 (D2a) a while back and it started and drive nice. It had the occasional getting too hot problem pop up(randomly).
Car has no reg, but he's got himself vic roads passes to get it from here to there(eg. to get from one side of town to the other to get it home) to fix it when/where he's had time too.
On some of those drives, it didn't overheat, on other drives it did.
After a bit of stuffing about turned out a tiny HG leak, so a secondhand head was sourced(apparently promised to be good) and it was fitted recently.
He did most of the work, and I helped where I could, mostly lending tools he didn't have. I was there when we fitted the head and bolted down, and I fitted the injectors and adjusted bump stops(having successfully done before) whilst showing him the process. I feel confident he's more than capable to do a lot of his own work judging by the work he'd done on his own.
It's his first build, but he's been pulling cars apart for a couple of years now(BMWs) and selling parts as a hobby.
His dad(my bro) owned the TD5 currently on my possession, and he loved driving it.
Just trying to establish his ability and eagerness here.

Anyhow. Before HG work, car started and ran fine, but as it was a new thing, and only ever on a permit, never pushed hard, driven fast(eg. 90ish on a freeway) accelerated carefully, etc.

After head gasket job, he had a really bad time trying to get it primed. Maybe two or three days trying to get it started with no luck. Multitude attempts at priming, both the 5 pump method and just waiting with IGN on till pump slowed/stopped pumping, but no luck. Tried start ya bastard spray, still no luck. I coached him into doing the sierraferry voltage check across the fuse for a reading on the pump. Turned out to be low 10s mW.. maybe 10.9mW or soemthing. Anyhow according to SF, too low for HP fuel pressure. So he bought an aftermarket pump from a good known(local) supplier that I've used for years. Pump fitted and then showing 20mW across the fuse. But still no luck in priming to start it.

He pumped and primed till he was exhausted.

He then got back to me and told of success, but only after rejigging the configuration of the lines out of the pump top.
he promised me that he hadn't mixed them up, but put them back the way it was set up going by the photos he sent me.
Anyhow, he's got them fitted according to correct orientation at least now. I'm still wondering if there were previously fitted wrong way, how could the engine run before.

With the HG job, he also changed the injector seals using the seals that came in the rebuild kit. Problem is that kit is a britpart kit!.
HG was a MLS from a known brand(can't remember but my seller says no problem with), just the rest of the kit was Britpart. I warned him of quality, but he was willing to just risk it for a short time and do the injector seals again if required .. just wanted to get it running to get RWC as soon as he can now.

So he'd got it started, it runs fine, but the problem is after a cool down period(say more than 30mins) it always needs a prime before trying to start it again. Even with a priming first, it will start straight up, but most likely not idle for more than a few seconds.

That is, no priming, won't start. Priming will get it to start, he says maybe a small amount of white smoke, but if he isn't there to give it a few revs, will die after a few(2-10 sec). Only trying to keep revs up it will stay running.
So far, no overheating again, but again being on permit(no reg) he can't really go a for a drive to see if it will show any leaking head gasket issues ... yet!
He's booked in for a RWC inspection after this weekend(2 or 3 sep), hes done a bit of work to get it close as possible to RWC, new windscreen, fix a few leaks(maybe still some but hard to really tell yet), some broken loose trims, etc.

Car is very clean and neat, and 'almost there'.
But the annoyance of why it seems to 'lose' lose pressure after sitting for a short time, or over night, then needing priming again.

Note my regular parts guy I trust pretty much 99.9%. He can sell aftermarket stuff, but only stuff that he doesn't get troubles returns or bad feedback with. I can't recall the brad of fuel pump, but he says he's not getting returns.

What nephew has changed, looked at and fixed:
did get and fit quality injector seals a few days ago(noting all parts form my regular supplier).
replaced air bleed valve.
replaced non return valve(actually fitted it, as the duckbill wasn't there, just the plastic tube bit was).
We did reuse his original FPR, which I guess could be a culprit, but again, was working no problem before HG work. New gasket and oring.

That I last saw: no fuel leaking issues. Nephew also can not see any fuel leaks.

Kind of an issue is that I now live 3.5 hrs away and can't really physically help easily .. I got to plan it.

Only thing he(we) haven't yet revisited again is to double check the FPR in any way. it's not leaking at least, but could it lose pressure, or maybe not building pressure enough, but just enough to get it to run?

Basically, if it's losing fuel pressure, where else can he check?

[V8Ian]

A Bosch fuel pump rebuild kit is now available, probably a better option than a Chinese copy.

[AK83]

A Bosch fuel pump rebuild kit is now available, probably a better option than a Chinese copy.

I'm loathe to think this is the problem, because now it starts fine, as long is it has pressure, which the new pump can provide.
Nephew confirmed that the pump brand is Intermotor, which I've had parts from prior on my Rover cars back in the day.

And to be sure if any one else has any clues what where to look ... when I say car needs priming to start, it's not the 5 pump prime method.
Just IGN on, wait for about 30sec for pump to build pressure, and then crank and she starts.
Don't do this, she won't start.

Oh! and yes, I will get a couple of those rebuild kits, as I now have two spare old pump bodies that could be easily made into ready to go spares.

[Tins]

Firstly, re the permit; if he has an UVP with the condition "prepare vehicle for registration in Victoria" there is no issue with driving it for the purposes of testing it, as long as the other conditions ( daylight, not for domestic purposes, etc. ) are met. I have done it often, D2 and OKA, and have "spoken" to the TOG guys who queried me. The OKA is not a subtle vehicle that slips under the radar. As long as he has a legitimate reason and ai not "difficult" with the officers he will be fine. Doesn't pay to abuse it, though, particularly if he is somewhere he is likely to encounter the same officers regularly. But testing repairs is the whole purpose of that particular permit. Relocation permits are a different matter, where "to and from" are specified.

If the car was running fine, heat issue aside, before the HG work was done then it seems to me that that is the area to focus on, and therefore I would look at the FPR. I'm assuming this is a 15 or 16P? When the car does start, does it run normally, i.e. can it be driven with no power loss etc? It may seem unlikely, but I believe it is possible for the supply line to the FPR to leak air in with no visible diesel leak out. This could cause the fuel to run back, thus requiring a prime. Also, check to see if the top of the starter has any diesel on it. It doesn't take much. The FPR also has a diaphragm which can deteriorate, so I'm wondering if the disturbance might have caused some issue, although I suspect it would leak visibly, I'm not certain.

Also, is it possible a fuel hose has been compromised, say pinched or kinked, in the head install process? I'm not familiar with the later fuel coolers, but I reckon that could happen on the earlier ones.

I take it you know the fuel filter to be good.

AFAIK it isn't possible to connect the lines at the pump incorrectly. But it's been some time since I did mine, and mine is the early one.

Wish Dave Fare was here. Good luck with it.

All this is just slightly educated guesswork on my part.

[AK83]

....

Wish Dave Fare was here. Good luck with it.

All this is just slightly educated guesswork on my part.

Yes re the permit ... he just doesn't want to push his luck.
Nephew live a min or two from Korroit Ck rd and uses it as his test track. There is one small bridge that allows a small amount of load on the TD5, and so far no problems either with drivability nor overheating.
It's approx 10 klm round trip for him, I reckon enough to get a good sense of how the HG job ended up and also if the fuel pump is working OK.

so far so good.

After the difficult process to prime it once HG job was done, first thing he did was to replace fuel filter. I told him to be weary of the rubber seal to be sure the old one came out ... etc, etc.

I'm thinking FPR too. As it was working before HG job, we used his old one ... the assumption being that nothing will have changed.
The 'good known' head he got came with FPR/block/lines/etc, but we still used his original one of his old head on the replacement head.

He has a few mates in the motor repair world, and head was pressure tested and crack tested by a head repair workshop(specialising in GM heads). They told him or slightly excessive play in valve guides, but should be acceptable.
The fact that the D2a drives ok(once started) me thinks shows that head work is acceptable. I warned him of the common practise NOT to skim head due to hardness complications too, and that process was avoided.

What I'm also thinking is that O ring that fits at the gauze filter. We did use the one that came in the Britpart kit, which seemed like a slightly wrong fit compared to the original type. I didn't like it, but we had no choice at the time.
I've texted him to be prepared to remove and double check the FPR again. And at the moment we don't have any way to set up a fuel pressure gauge to see what happens to fuel pressure, both when running and after sitting for this 15-30(ish) min period after which it requires priming again(ie. IGN on for a good 15-30 sec, not 5 pedal pumps).

he reckons zero fuel leaks anywhere, FPR tank, filter... etc.

[sierrafery]

Hi, i can't explain why but i've seen a case when with similar symptom the problem was the filter head, seems that there is one scenario when there's a crack in it and it's sucking air instead of leaking...might be on the air bleed connector path, i dont know just that after a long saga with startig issues changing the filter head was the cure provided it was an extremely clean work with the injector copper washers)

Another thing which can cause such symptom is if the loop shown in the pic is choked, the vacuum in the tank can have a bad effect on the pump's initial pressurising... a simple test for this is to remove the fuel filler cap and try to start it that way... if it starts well the problem is there or with other component of the breather system

though as the problem appeared after the HG job i'd suspect something related, maybe the copper washers like in this case(recently changed) but with different symptom https://www.aulro.com/afvb/discovery-2-a/300179-td5-losing-power-but-not-completely-4.html#post3232389

[discorevy]

If the fuel lines were removed and replaced at the union it would be possible to have them mixed up, top one goes back to chassis rail and lower one to fuel cooler.

Having said that, it sounds like more of an incorrect cam timing issue.

Of course, it's also worth making sure the fuel injector O rings aren't leaking (oil level?)

[sierrafery]

Having said that, it sounds like more of an incorrect cam timing issue.


That was my first thought when the HG replacement was mentioned but i was affraid to say it [bighmmm]

[AK83]

I was worried about cam timing.
Both myself and nephew felt 99.9% confident we have it right tho.
I've done a few head gaskets, but never TD5. And I've done my Tdi belt twice now without mis-timing ... but you never know if you missed some tiny detail.

But what has me perplexed is that it runs so well once started.
Wouldn't mis timed also equal not so smooth running ... that is some mis step or hiccup whilst running.

And also, back to the point that if the start sequence is ... IGN on, wait a few sec for pump to prime, then hit starter and it starts straight up ... this would eliminate any issues about timing
That is, if timing was out at all, then priming shouldn't help in starting the engine? Is that an accurate thought process?

Remember the point of the post is twofold.

1. without a short wait for the pump to prime the fuel lines, she wont' start. That 10-30 sec wait always gets it started first go.
2. after sucessful start, she wont' then idle, it needs the driver to blip accel for a short time to get through the problem(eg. air in fuel). he says a small amount of white smoke after starting and running, which then disapears and car idles fine(and drives fine)

I did read of some folks having filter head issues too. filter head in his TD5 is pretty much brand new looking, ie. no corrosion or anything like that, and it was never touched with the HG job.

My problem here is that I can't easily get down there to help him. I'm thinking to get him to bring it up here and I can spend some time looking at it, even swapping a few bits out of my TD5 to see what would change.

Would a fuel pressure test reveal anything?
I'm thinking that if I recommended nephew to get himself a pressure gauge, hook it up, start car, get fuel up to pressure and wait to see how it drops over the course of this half hour or so(his description).
How much drop(if any) would be acceptable?

My understanding is that fuel pressure at the FPR shouldn't fall(at least to much) as it's needed on start up
he fitted a new duckbill, non return doodad down back at the filter head. I didn't confirm he's fitted it into the correct port tho. He's a smart cookie tho, I have confidence he can figure it out and he has a copy of RAVE to folow diagrams and suchlike.
With this duckbill thingy fitted, I'd assume that if its losing fuel pressure, it wouldn't be back into the filter head, ie. beyond the duckbill. And if no fuel leaking then it must therefore be internal within the FPR?

I'm suspecting the Britpart gauze filter o-ring here.

[Tins]

While I bow to the greater knowledge of both dr and sf, my issue is that a mistimed cam won't miraculously fix itself once the engine starts. I know they can run a tooth out, interference clearances willing, but you'll notice. In another life I did heaps of OHC and DOHC heads. While I have never done a TD5 (🤞🙏😱 ) I don't see the principles as being different, and anyone with some tool competency and the right tech info should be able to manage it.

I know the FPR can be awkward to get at, but that's my gut as well, especially f you have a bad feeling about that O ring. I know this is all remote guesswork, but to me it sounds like the fuel is draining back a little. and allowing air in. So, a question: if he shuts it off, will it restart straight away? That is, does this problem only manifest if the car stands for a while, or is it a constant? To me, the fact that he does not have to do the five pump purge cycle is significant. I have heard of this pointing to a weakness in the pump, but his issues began with the HG job, and once again I would focus on that work, although it is a Disco so coincidences abound.

Re measuring fuel pressure: I don't have the specs at hand, but I believe it should maintain some, at least a head to keep fuel in the head system. 15/16P are different to 10P, but not a lot.

There is a series of vids covering a lot of the fuel issues. He's a knowledgable chap.


https://youtu.be/yDdsmG-50z8'si=Rtlm9RcafobWLVJ1


https://youtu.be/puipyCJnTUg'si=IGse2hR7dfrlFwkj


https://youtu.be/KMMbHWY8Qqk'si=LHB4mp1hX5Her-qR

[Tins]

Totally random thought, but mine became slow to start when I damaged the wiring going to the CPS. It would crank for a while before firing. Sometimes the MIL would come on, but rarely. Seeing he was in that area it's worth a thought. Unlikely, I know, but....

[AK83]

if it's shut down and restarted in short time, it starts no worries. Short time = anywhere withing about 10-15 min range ... give or take and approximately. He's never really measured, just done it.
So in that sense, yeah, she starts no worries if restarted soon after shut down.
Again without actually measuring, just a rough figure, eg. 10-30mins ... maybe 15-30 min range ... or whatever beyond the shorter time period being off ... no, she needs the ign on and wait a few seconds for fuel to prime back up.

Last time I was down there, I had ign on for about 20 sec, and hit starter and it started with maybe 5 sec of cranking, but then died maybe 10 sec later.
Went to start it again but then nephew took over and used hand to keep a bit of revs up. I didn't notice(or really pay attention too) the any white smoke that he later told me about, but if it was, was very minimal as it wasn't 'bleeding obvious'.

What I'm thinking of doing is using a couple of quick connects onto fuel hose with a pressure sensor (eg. electronic VDO style) to intercept the the quick connect inlet hose and a gauge to keep an eye on fuel pressure..

Hes seen the 'difficulty' of doing the FPR, but as I recall(having done twice) the only difficult part(if you dont' remove the inlet manifold) is having two hands in there whilst trying to hold bolts that fall out gasket that is impossible to get a hand or finger too and zip up the bolts ensuring the gasket is correctly seated.
Actually getting to the individual parts is OK ... so if using the rubber band method to hold bolts and gasket is used, shouldn't be too too hard .. just "annoyingly not made easier"

ps. considering he's into breaking BMWs ... LR is easy peasy by comparison! [biggrin]

IIR rightly, the britpart gauze filter oring was a stubby fat thingy, just shy of the correct size of the recess(half a mm or so) as FPR was fitted with head on bench, and seeing that it would compress well being such a thick cross section, I(we) assumed it would seal..
This is why I(we) think if there is some fitting anomaly with the gauze filter this could be it.
I've had a look at the FPR and head here in my shed, and I can sort of see it, but still don't make sense .. if the oring is just plain leaking due to wrong size, it just leaks into the inlet and temp sensor port .. so really no reason for any loss of pressure.

BUT! If the added thickness of the oring(which it was compared to the old one) doesn't let the FPR seat absolutely correctly, the very think strip of the gasket could be comprimised between inlet/sensor port and the return port.

I had a quick look at discovery2.co.uk and his images re FPR and for sure the britpart o ring sat a lot more proud of the head surface.
I guess this is why I question the gauze oring .. if it is leaking back into the inlet port, question is it must be important to have a seal there, otherwise why have it in the first place. To me it kind'a doesn't make sense. The gasket 'seals' the inlet/sensor port area anyhow with it's raised seal section .. so why is the gauze filter really there.

Anyhow, this may be the plan for this Monday(I think). As long as he can get his hands on oring and gasket. a couple hrs work and hope it's the issue for him. I'll get back once he's done it.

[sierrafery]

I presume you are aware that the FPR's metal gaskets are not reusable at all, once removed it will never seal well no matter how much sealant you use and even if it doesnt leak around the internal flow is mixed up

[V8Ian]

Don't the Td5 and Ford Barra share a common FPR?

[discorevy]

if it's shut down and restarted in short time, it starts no worries. Short time = anywhere withing about 10-15 min range ... give or take and approximately. He's never really measured, just done it.
So in that sense, yeah, she starts no worries if restarted soon after shut down.
Again without actually measuring, just a rough figure, eg. 10-30mins ... maybe 15-30 min range ... or whatever beyond the shorter time period being off ... no, she needs the ign on and wait a few seconds for fuel to prime back up.

Last time I was down there, I had ign on for about 20 sec, and hit starter and it started with maybe 5 sec of cranking, but then died maybe 10 sec later.
Went to start it again but then nephew took over and used hand to keep a bit of revs up. I didn't notice(or really pay attention too) the any white smoke that he later told me about, but if it was, was very minimal as it wasn't 'bleeding obvious'.

What I'm thinking of doing is using a couple of quick connects onto fuel hose with a pressure sensor (eg. electronic VDO style) to intercept the the quick connect inlet hose and a gauge to keep an eye on fuel pressure..

Hes seen the 'difficulty' of doing the FPR, but as I recall(having done twice) the only difficult part(if you dont' remove the inlet manifold) is having two hands in there whilst trying to hold bolts that fall out gasket that is impossible to get a hand or finger too and zip up the bolts ensuring the gasket is correctly seated.
Actually getting to the individual parts is OK ... so if using the rubber band method to hold bolts and gasket is used, shouldn't be too too hard .. just "annoyingly not made easier"

ps. considering he's into breaking BMWs ... LR is easy peasy by comparison! [biggrin]

IIR rightly, the britpart gauze filter oring was a stubby fat thingy, just shy of the correct size of the recess(half a mm or so) as FPR was fitted with head on bench, and seeing that it would compress well being such a thick cross section, I(we) assumed it would seal..
This is why I(we) think if there is some fitting anomaly with the gauze filter this could be it.
I've had a look at the FPR and head here in my shed, and I can sort of see it, but still don't make sense .. if the oring is just plain leaking due to wrong size, it just leaks into the inlet and temp sensor port .. so really no reason for any loss of pressure.

BUT! If the added thickness of the oring(which it was compared to the old one) doesn't let the FPR seat absolutely correctly, the very think strip of the gasket could be comprimised between inlet/sensor port and the return port.

I had a quick look at discovery2.co.uk and his images re FPR and for sure the britpart o ring sat a lot more proud of the head surface.
I guess this is why I question the gauze oring .. if it is leaking back into the inlet port, question is it must be important to have a seal there, otherwise why have it in the first place. To me it kind'a doesn't make sense. The gasket 'seals' the inlet/sensor port area anyhow with it's raised seal section .. so why is the gauze filter really there.

Anyhow, this may be the plan for this Monday(I think). As long as he can get his hands on oring and gasket. a couple hrs work and hope it's the issue for him. I'll get back once he's done it.

Jeez Arthur, I'm thinking you maybe just enjoy the faffing about.

Even if I did have the time, I reckon I'd rather spend it doing something else.






Don't the Td5 and Ford Barra share a common FPR?

Yep, along with VW's Audi and a couple more Bosch part number: 0 280 160 575

[AK83]

I presume you are aware that the FPR's metal gaskets are not reusable at all, once removed it will never seal well no matter how much sealant you use and even if it doesnt leak around the internal flow is mixed up

Yep. thats not in question.
What I can't get my head around tho is the oring. It kind'a doesn't seem to be doing anything. That is, it seems to seal the gauze filter and the inlet head in the port, but really only from the inlet port istelf, which is about 20-ish mm sq and has the temp sensor in it too.

My very vague memory of bolting the fuel block back on was that the oring stood out much more than what disco2.co.uk shows in his photo.

And, for sure I like faffing about ... I reckon the major reason for my will to live.
Two more weeks to go, and old residence is gone, and my finances will allow a whole lott'a'faffing to come [biggrin]