Thread: fuel pressure loss?

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

Originally Posted by V8Ian

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.

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.

Originally Posted by Tins

....

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.

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 Td5 losing power but not completely

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?)

Originally Posted by discorevy

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

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.