Xantia V6 broken exhaust (update: and rough low rpm running)

[Mandrake]

Are the spigot the same as those on the fuel filter?

Bother. On further investigation the spigot on the fuel filter and fuel pump are not the same:

http://www.mister-auto.co.uk/en/fuel-fi ... 2!161.html" onclick="window.open(this.href);return false;

That fuel filter arrived a few days ago and its nothing like the one in the picture! In fact its black plastic and the spigots DO look the same as the ones on the fuel pump, and from what I remember of the filter I have on the car now (which is an aluminium casing not plastic) the filter I received is the correct size and shape, so the picture on the website is completely wrong. So the good news is I should be able to use the old filter spigots to make up a T to get the fuel pressure gauge into circuit, and also help me do a volume delivery test.

While I wait patiently for a chance to run my tests I've been thinking through the possible symptoms of a fuel pump problem and doing a bit of research and I'm going to be bold and call two weak fuel pumps as being the cause of intermittent lean running. I'm still going to go through with my pressure and delivery tests BEFORE buying a new pump (I'm looking seriously at the £62 Bosch one I linked earlier after doing some reading on the after market Bosch pumps - no way am I paying Citroen's price ) but I think I might be right here.

The following article among others was quite interesting:

http://www.agcoauto.com/content/news/p2_articleid/195" onclick="window.open(this.href);return false;

What that and other reading revealed (some things I knew already but hadn't considered in this context) was:

1) These type of in tank pumps rely on the head of fuel above the pump inlet to feed them - they can't suck like diaphragm pumps. Low head of fuel due to low fuel possibly made worse by a leaky swirl pot valve (preventing the swirl pot fully filling except when the tank is full) means a low fuel head above the pump and reduced flow if the pump is weak.

Thus a marginal pump will struggle with delivery more with a low fuel tank than a full tank, while a healthy pump will have so much excess delivery margin that low tank or full tank won't matter.

2) These pumps apparently also rely heavily on both the flow of fuel through them and the mass of fuel sitting immediately around them to cool them. A number of sources I've read suggest that constantly running the tank near empty can cause the pump to overheat and in the long term damage will be done.

If you only have a little bit of fuel in the tank and it is circulating through the pump, fuel rail and back, it's absorbing heat both from the pump and from the fuel rail which is heat soaked in the engine bay, after a while that circulating fuel will heat up a lot. If you have a full tank there is a far greater fuel mass to absorb that heat and radiate it out through the fuel tank walls - effectively the fuel mass acts like a heat sink and the pump runs cooler.

3) Symptoms of a weak pump are often temperature dependent - this is particularly the case with worn out brushes where they might contact when the pump is cold but when the casing expands with heat brush contact on some brushes becomes marginal and pump performance drops due to high resistance or entire segments loosing contact and in some cases the pump becomes noisy as well. (Probably due to some segments no longer contacting) Some faulty pumps will even fail completely after half an hour of running and not work again until they cool down.

Because weak pumps symptoms can get worse or only appear when hot, measuring pressure and volume delivery on a cold pump on a car that hasn't been driven that day is not necessarily valid, especially in cold weather. I did measure the delivery of my original pump once at 1.2 litres / min, (should be 2 litres / min so already quite low) but that was when COLD, I never tested it with a really hot engine when the car was symptomatic, so it could have been dropping even lower.

So how does all this fit in with symptoms ?

One correlation I HAVE definitely noticed and reported before (also observed by stevieb too) is that on a long drive (long enough for engine bay heat soak) with the fuel tank nearly empty performance can often sag quite a bit, and not improve even after multiple 10 minute engine off rests - and yet filling up the tank with fuel with the same 10 minute engine off rest the performance will improve almost immediately - as soon as you drive off the forecourt the performance is dramatically improved. Why ?

1) The pump now has a full fuel head above it. 2) The pump is now submersed with a tank full of fresh, cold fuel, so is quickly cooled down and probably runs significantly cooler on an ongoing basis due to the extra cooling from the full tank. So whether its the increased fuel head, cooling the pump down or a bit of both doesn't really matter - in both cases it points to a faulty pump.

There is definitely a correlation between how full the tank is and how well the car runs - it runs best on a full tank and starts to get a bit more symptomatic and cranky when there's less than about 20 litres left.

Another correlation I have definitely noticed is the car ALWAYS runs better on very cold days, (near zero) whereas on hot days especially if you do a lot of long distance 30mph stop start driving (enough to get the radiator fans kicking in and out) performance is worse. Again - could the fuel pump be struggling when it heats up, and getting by when its cold ?

Another thing I notice is that when its running too lean under WOT the O2 sensor reading is quite "noisy" - at first I thought that might be due to a misfire, but I'm now wondering if that's due to fuel pressure pulsations. When the pump output is sufficient for the pressure regulator to be open and regulating correctly the regulator smooths out the pulsations of pressure that the pump generates. If the delivery from the pump is too low to maintain regulated pressure however, the pressure regulator will close and the pressure pulsations of the pump will not be filtered out as much meaning that fuel pressure will go up and down at the commutator rate of the pump. Could this be reflected in small rapid variations ("noise") in the O2 reading ? Maybe...

This car was performing fine when I first got it, so why would the pump choose 6 months into me owning it to die ? Thinking back there is one thing I did to it almost constantly the first 9 months I had it - I ran the petrol tank nearly empty nearly all the time. I would run it for about 20-30 miles AFTER the low warning light had come on and then only put in £20 maybe £30 at most to get by. So it would have been running between 5 - 20 litres nearly all the time, unless we were specifically going on a long trip.

From the research above it seems this puts a lot of strain on the pump and can make it overheat - maybe it was the final straw for a 15 year old pump. A new pump might have taken this abuse for 5-10 years but it was too much for an old one. Another factor was that was all ASDA fuel, so you could get into debates about whether there was any water or particulate crap in the fuel that could have also contributed to pump wear (remember the fuel filter doesn't protect the pump itself, it only has an inlet sock which only filters down to 70 microns) - maybe just running it low on fuel all the time was enough.

So I did a flow test on my original pump 6 months ago and it was quite low so I replaced it - with another second hand pump... In hindsight not a good idea when trying to diagnose a tricky problem, although the price of a new genuine pump was not an option at the time. (at least not from Citroen) I also didn't flow test the replacement pump, which I also regret, so for all I know it could be worse, or it could be more intermittent with heat, have greater brush wear etc... (it was from a 160k car, mine has only done 110k so potentially the pump is more badly worn than my original...)

I think the same in-tank pump is used across all Petrol Xantia's - so why don't more people notice problems with weak pumps ? Probably because the V6 places the most demands on the pump under WOT of all the Xantia's. A weak pump which might struggle to meet delivery requirements for the V6 may not exhibit any symptoms on a 2 litre Xantia.

One final issue I've noticed with both pumps is the leak-back valves don't work properly, and sometimes don't hold fuel rail pressure for long after key off. (confirmed with the fuel pressure gauge) This can cause difficult starting when hot due to vapour lock, and I do see these symptoms too. From what I've read this is also a symptom of a pump that has been mechanically worn out through impurities in the fuel. (The ball valve and seat is damaged) The only way to solve that issue is fit a new pump or an external leak back valve.

So do I really just have two old tired pumps that are struggling to keep up with the demands of a V6 especially when the pump is hot ? Could well be. I'll know for sure when I get a chance to run my tests, and if it proves to be the case then I think the moral of the story is that a 2nd hand fuel pump is a waste of money when its 15 years old, its probably as worn as the one you're replacing!

[stevieb]

Sounds like you've made progress Simon

I've stayed away from this thread for a couple of weeks partly due to being as busy as a busy thing with work, but also to try and find some clarity with my own car - my head was filling with possibilities and potential, none of which were necessarily specific to my own vehicle - so I've had time to clear out all the other ideas from my head and just concentrate on my own. It's been very helpful

I too have begun accepting I have a weak pump. Switching away from Shell fuel cured a multitude of sins, not least of which was the unpredictable nature of the supply of power (usually low I might add), but I've had a return to some of the symptoms I had before I cleaned up the fuel pump terminals. Most of the time the car flies along, particularly from a cold start, but warm starts sometimes create a flat spot and a return of the 3000rpm drone. This has been worse with Esso fuel than the Texaco tank-full I added last week, and presumably this was being exaggerated even more by Shell fuel - as per earlier comments if fuel supply is being impeded by additives in some way then it all makes sense (I haven't used BP for years, so can't comment on that). But it's definitely a warm start issue, and is sometimes helped by starting the car and leaving the engine running for a minute or two before pulling away, possibly helping to shift any problems in the fuel rails (vapour locks etc) before they affect running.

Interestingly, I had a series of 7 or 8 warm starts the other day - but each one after a short town-journey - and the car performed faultlessly after each one. The "warm pump" theory holds plenty of water (or maybe petrol) as far as I'm concerned, as on this occasion (a cool day) the pump probably never had chance to get warm despite the CTS and oil temp sensor both reporting the engine reaching working temp. I too have previously run the car a lot with the low fuel light on, and normally the car would've been like that in this case, but on this occasion I still had over half a tank left which was presumably heat-sinking nicely

So. To new pump or not new pump... Hmmm....

[stevieb]

Well my quick search for a pump has just got very intriguing. Apparently my car should have the metal-ring-secured pump - part no. 1525 C5 - this is according to Peugeot, and going on my VIN number. However, I don't have a metal-ring-secured pump, and my pump doesn't precisely match the pictures of the above part number. Considering the fuel line to the filter had been butchered before I bought the car I wonder if the tank has been swapped at some point...

EDIT - I may have spoken too soon. searching the part number for my securing ring brings up the correct part, so it may just be the picture that's misleading, even on Peugeot's own parts database

EDIT 2 - I forgot to say above, that mine was also a bit more likely to misbehave on damp days. I've presumed this might be a bad earth on the fuel pump supply, but as yet haven't managed to find out where the earth is. This is my next plan...

[Mandrake]

Sounds like you've made progress Simon

I've stayed away from this thread for a couple of weeks partly due to being as busy as a busy thing with work, but also to try and find some clarity with my own car - my head was filling with possibilities and potential, none of which were necessarily specific to my own vehicle - so I've had time to clear out all the other ideas from my head and just concentrate on my own. It's been very helpful

Fair enough, I know what you mean by an endless stream of what if's and maybe's, it can get a bit much.

I too have begun accepting I have a weak pump. Switching away from Shell fuel cured a multitude of sins, not least of which was the unpredictable nature of the supply of power (usually low I might add), but I've had a return to some of the symptoms I had before I cleaned up the fuel pump terminals. Most of the time the car flies along, particularly from a cold start, but warm starts sometimes create a flat spot and a return of the 3000rpm drone. This has been worse with Esso fuel than the Texaco tank-full I added last week, and presumably this was being exaggerated even more by Shell fuel - as per earlier comments if fuel supply is being impeded by additives in some way then it all makes sense (I haven't used BP for years, so can't comment on that). But it's definitely a warm start issue, and is sometimes helped by starting the car and leaving the engine running for a minute or two before pulling away, possibly helping to shift any problems in the fuel rails (vapour locks etc) before they affect running.

Interestingly, I had a series of 7 or 8 warm starts the other day - but each one after a short town-journey - and the car performed faultlessly after each one. The "warm pump" theory holds plenty of water (or maybe petrol) as far as I'm concerned, as on this occasion (a cool day) the pump probably never had chance to get warm despite the CTS and oil temp sensor both reporting the engine reaching working temp. I too have previously run the car a lot with the low fuel light on, and normally the car would've been like that in this case, but on this occasion I still had over half a tank left which was presumably heat-sinking nicely

So. To new pump or not new pump... Hmmm....

Good timing - I've been out today running a test on the fuel pump in the car at the moment (a 2nd hand one fitted last August) so I have a little bit more data to go on.

Last year I measured the volume delivery of my original pump at 1.2 litres/minute against the PSA quoted spec of 2 litres/minute - eg only 60% of what it should be. From reading I've done the rule of thumb is that an in-tank pump is typically designed to have about a 2 to 1 performance margin over peak demand required by the engine - eg if you pinch off the return line you should be able to reach nearly twice normal fuel rail pressure, and the volume delivery (not pinched) should be about twice what full WOT would demand.

So that being the case, 60% of rated delivery is quite marginal indeed, leaving almost no headroom or perhaps no headroom if the design margin wasn't quite as generous. When I fitted this 2nd hand pump I never did measure the delivery under load. Today I measured it, and got a figure of 1.3 litres/min. So very slightly better than the original, (at least when the test was performed) but still within the margin of error given that the conditions of the test (temperature, voltage etc) are no doubt slightly different.

This test was (unfortunately) done on a cold windy day with the engine and pump also cold, so if we assume the pump performs best when cold and worse when hot (which seems to be the case, and seems to be the way pumps fail, first only when hot, then completely) then this is a BEST CASE figure, which may intermittently be much worse when the pump is hot. If the brushes are badly worn in the motor so they are barely contacting, the pump RPM could be varying all over the place when it gets hot causing random variations in fuel delivery.

The reason I replaced my original pump in the first place was because I wasn't happy with the volume delivery being so far below spec - it looks like the 2nd hand replacement is really no better - unsurprising when it has done 50k miles more than my pump had!

So if poor fuel delivery is the underlying cause of the lean running then it makes perfect sense that swapping the pump made no real difference when the replacement is also worn and suffering from low delivery to within about 10% of the other pump. (Assuming the 2l/min figure is accurate - it's taken directly from ES9J4 specifications documents)

Another thing I noticed while running the pump manually without the engine and listening to it is there is a lot of noise that intermittently comes and goes and sounds like the petrol in the swirl pot is being beaten into a frenzy, possibly cavitation in the pump - it sounds a lot like the test pump in the shed did when the petrol level was low - except my tank is 3/4 full at the moment.

I was already suspicious that the swirl pot valve doesn't seal properly on this 2nd hand pump assembly as soon after fitting it I noticed that a hard right turn then accelerating with less than 15 litres of petrol left sometimes resulted in complete cut-out for a couple of seconds, something I never had with my original. Seemingly the input of the pump is running dry in those conditions.

I would really like to measure fuel pressure in the car while driving under load and correlating with a lean O2 reading and lack of power, but it looks too difficult to set up the test in my current circumstances. To measure the return flow was easy - I disconnected the return hose from the top of the pump and connected it to my new fuel filter (which has the same click-lock fittings as the pump and the fuel rail ) and then a fuel hose from the filter into a 1 litre measuring jug, timing how long it takes to fill. By routing it via the fuel rail the pressure regulator insures the pump is being delivery tested under the full 3.0 bar load.

To measure fuel pressure I would have to attach both fuel filters underneath the car in series with a T junction in between them which goes to the pressure gauge - there is enough gap to pass a hose up past the tank and through the fuel pump access hatch, thus bringing the teed hose safely into the car - but to do this I need the car up on ramps, and I can't safely get it up on ramps half on the pavement on the steep street I live on. That of course and the damn weather which is constantly cold, windy, and threatening to rain...

So I'm in a bit of a quandary now - I've confirmed the 2nd hand pump has the same poor delivery volume, but I can't easily confirm if the fuel pressure is actually dropping under WOT load, although it seems likely that it is. When I went for a drive today after doing the fuel pressure test (and having the battery off) it was running fairly well but the lean WOT episodes were still there, and were worse at times and better at other times. Lack of performance definitely correlates perfectly with indicated lean running under load.

I'm trying to decide now whether to plump for the Bosch pump based on the low volume delivery evidence (and other clues) alone and take the punt that it is low enough to indeed be causing fuel rail pressure to sag, or to make more of an effort to set up a proper test rig to measure fuel rail pressure on the move.

I've also been chasing the near stall when tapping the throttle at idle and the stumble at idle when flooring the throttle - I know now its not the TPS, and what I saw today is that even a light tap of the throttle which causes the engine to try to stall causes the O2 reading to swing momentarily very lean - so both are a "lean stumble" where the sudden opening of the throttle increases the air flow suddenly but the fuel injected does not keep pace so the mixture goes lean.

In the shower yesterday I was thinking about why it might stumble when flicking the throttle at idle and I suddenly remembered an interesting fact about the injection design. This engine is a "pair fired sequential" injection system, which means that injectors always fire in pairs, and it cycles through each of the three pairs 1,2,3,1,2,3,1,2,3 etc...

EXCEPT during cranking and acceleration enrichment, (when quickly opening the throttle) where it operates in a "group fired" mode for a fraction of a second where ALL 6 injectors fire simultaneously. The consequence of this should be obvious - if the fuel delivery is marginal and can barely keep up to regulated pressure when only one pair of injectors is firing at a wide pulse width, it will not cope when for (say) 1/4 of a second all 6 injectors are firing simultaneously with wide pulse width - pressure may drop as much as 3x as much and cause a lean stumble due to the mixture being a lot leaner than the computer anticipated.

This could easily explain why I'm seeing a stumble when I snap the throttle - the instantaneous fuel delivery to supply 6 injectors at once simply isn't there.

I know the leak-back valves in both pumps don't work properly either, (and experienced difficult hot starting again today where it started but kept trying to stall) so I'm really tempted to just replace the damn thing with a new Bosch pump and see how it goes... The Bosch pump is only twice what I paid for the 2nd hand one which may in hindsight have been a waste of money and time...(especially if it set back the diagnostic process by six months by replacing a faulty component with another faulty component... )

[stevieb]

...so I'm really tempted to just replace the damn thing with a Bosch pump and see how it goes...

I'm having trouble with the part numbers - early Pugs were all over the place, but then settled down for a while (around my part number - 1525C5), but then they acquired the "DEPOL CEE 2000", which changed them again. I presume DEPOL is the depollution system?

I can find non-Pug parts for all versions except mine, or at least it seems that way...

Are you sure the Bosch one you've found is right Simon? Are Citroen pumps a little easier to pin down?

I have the VDO number off mine, but Googling that doesn't help much either. If it's any use to you, it's 228.222/8/9.

[Mandrake]

...so I'm really tempted to just replace the damn thing with a Bosch pump and see how it goes...

I'm having trouble with the part numbers - early Pugs were all over the place, but then settled down for a while (around my part number - 1525C5), but then they acquired the "DEPOL CEE 2000", which changed them again. I presume DEPOL is the depollution system?

I can find non-Pug parts for all versions except mine, or at least it seems that way...

Are you sure the Bosch one you've found is right Simon? Are Citroen pumps a little easier to pin down?

I have the VDO number off mine, but Googling that doesn't help much either. If it's any use to you, it's 228.222/8/9.

According to service.citroen.com (do you have an equivalent you can use to look up parts based on your VIN ?) the fuel pump for mine should be 1525 77 which is the complete assembly including the fuel level sender. (For an eye watering £192)

Here is my original fuel pump which is sitting in the shed at the moment:



In case you can't make it out, the VDO number is 228.222/8/6 - so slightly different, although what the difference is who knows. I'm sure this pump would work for your engine, but whether it would fit the space in the tank is a different question, especially when yours is a later D9.

The Bosch pump I linked to on mister auto says it matches 1525 77 (which is apparently used by some Peugeot's too, maybe not yours) and they're generally pretty good at getting the parts listings correct. So for me anyway, this appears to be the correct pump.

Mister Auto also list three Valeo replacements - one a pump motor only, the other two complete assemblies, although I'm not sure why Valeo make two different pump assemblies of such different price for the same pump type! (Why would you buy their £196 one when they also make a £116 one)

http://www.mister-auto.co.uk/en/fuel-pu ... _g458.html" onclick="window.open(this.href);return false;

I know there are a lot of Valeo supporters but I really can't justify the extra cost, and its not as if Bosch make junk, they are a good tier one supplier too...a new Bosch pump is still going to be 10x more reliable than a 15 year old second hand one that has done 160k miles.

PS when I look up a 406 V6 (190HP) on mister auto it shows four different Bosch pumps - try doing a number plate lookup on mister auto with your number plate and see which one matches...looks like they are different to the Citroen ones!

http://www.mister-auto.co.uk/en/fuel-pu ... _g458.html" onclick="window.open(this.href);return false;

[Hell Razor5543]

Simon, sorry to go off topic, but where do you get your Lexia updates from? I want to update mine, but I don't want it to then try and register and throw a wobbly. Thanks.

[stevieb]

Bosch list two for mine - neither the same as yours Simon (I note Bosch only list one for yours). In my case one states is has fuel return, one without. Mine has two spigots, but isn't the "DEPOL CEE 2000" which came later, so I'd presume it's the non-return one (which I'm guessing has a third spigot somewhere). Dunno.

[Mandrake]

Do you have two fuel hoses on your fuel rail - one to the back left and one to the front left ? (Looking into the engine bay)

If so its a return type system. In fact as far as I know the ES9J4 are all return type systems as the 2nd hand fuel rail I got and fitted was from a 406 D8

If it lists some as return-less (only one fuel hose to the rails) that's probably for the later ES9J4S engine.

[stevieb]

Do you have two fuel hoses on your fuel rail - one to the back left and one to the front left ? (Looking into the engine bay)

If so its a return type system. In fact as far as I know the ES9J4 are all return type systems as the 2nd hand fuel rail I got and fitted was from a 406 D8

If it lists some as return-less (only one fuel hose to the rails) that's probably for the later ES9J4S engine.

I think I've sussed it. Reading between the lines all the aftermarket manufacturers are missing a year in their products. Using the Delphi ecatalogue, they have a pump from 95-98 (totally different to mine), then another from 95-97 (like ours, build code ref: ->RP7482), and another like ours from 97-98 (build codes RP7483 - RP7968). The next one is 2000-2004 and includes the ES9J4S (build code RP8541>-). I see a gap, right where my car rolled off the production line in 1999. My build code falls into that gap too...

I think this is going to take some digging to suss out what changed. If the later cars used the same tank/gasket/clamp, then it's fair to assume the physical fit should be the same. Then I need to work out whether the electrical and fuel connections are right. This is working out harder than I thought...

[Mandrake]

Argh, don't you just hate trying to figure out which is the correct part in those circumstances!

So much simpler on the Xantia - I think all the petrol Xantia's share the same pump as they all have the same petrol tank, fuel gauge and I think they're all return type systems...

If you don't mind waiting a few weeks I should have an answer as to whether the pump is the underlying problem or not. By then I should have either been able to do an under load fuel pressure measurement that would prove it, or just gone ahead and replaced it.

Time is ticking away on my MOT - just over 4 months left and I still don't know for sure what caused it to barely scrape through the last emissions test with a bit of fudging. I need to get this lean running sorted ASAP so I can take it for an early emissions test to find out whether my cat is stuffed or whether it was just misfiring during the test causing the high emissions.

[stevieb]

Argh, don't you just hate trying to figure out which is the correct part in those circumstances!

So much simpler on the Xantia - I think all the petrol Xantia's share the same pump as they all have the same petrol tank, fuel gauge and I think they're all return type systems...

If you don't mind waiting a few weeks I should have an answer as to whether the pump is the underlying problem or not. By then I should have either been able to do an under load fuel pressure measurement that would prove it, or just gone ahead and replaced it.

Time is ticking away on my MOT - just over 4 months left and I still don't know for sure what caused it to barely scrape through the last emissions test with a bit of fudging. I need to get this lean running sorted ASAP so I can take it for an early emissions test to find out whether my cat is stuffed or whether it was just misfiring etc causing the high emissions.

Two weeks 'til my MoT I was hoping to have a new car by now, but the day job isn't quite lucrative enough yet, and this car is eating away at my attempt to save up a deposit, so I'm getting nowhere fast... Road tax is due end of the month too...

I think as mine is behaving more than it doesn't, and the MoT place is only five minutes away, I might just get through. As long as it's not a warm day

The other thing I've found, that may be coincidental or down to typos somewhere in the chain of data, is that later pumps work at 3.6bar, not 3.1bar. These seem to be the DEPOL ones as far as I can tell. How the hell I differentiate this elsewhere is anybody's guess. Maybe I need to check this again in the morning after a gallon or two of super strong tea - the more caffeine the better to try and understand this lot! Now, do I need a or a ?

[Mandrake]

Yes, I noticed that the listing for the Valeo pumps for the Xantia say 3.5 bars too.

Which doesn't make a lot of sense when the pump itself in a return type system doesn't have a pressure regulator - the pressure regulator is in the front rail on the left hand end, and its that, not the pump that sets the operating pressure. (Provided the pump has sufficient delivery and pressure producing ability to exceed the regulated pressure so the pressure regulator can open to regulate the pressure)

My guess is that they're saying that the pump is capable of operating at "up to" 3.5 bars, even though the pressure regulator will limit it to 3.0 bars. AFAIK all ES9J4 run at 3.0 bars.

On the other hand on a non-return system the pressure regulator is in the pump assembly - you can actually see it in one of the pics of the Peugeot pumps. (Not yours though)

[stevieb]

A pump starting at 3.5bar leaves a lot more headroom before it drops below the minimum 3.0bar - allowing the manufacturers to offer nice long warranties, safe in the knowledge that the pump will last long enough even if the wear rate is very high.

A pump designed for 3.1bar (as most of the others seem to be) leaves a lot less headroom before it starts to drop below the minimum required (potentially being seen at the fuel rail schrader valve), so it'd have to be better constructed to last the length of the warranty...

Or maybe perceived wisdom changed and it was decided that making the pressure regulator work harder was a better way to keep it clean by flushing it out frequently. After all, the regulator only regulates the pressure by letting any excess leak-off back to the tank.

Dunno. Just a couple of thoughts.

EDIT - According to Servicebox, mine's EEC 95, not EEC 2000, so presumably the DEPOLL pumps are unsuitable, depending on what exactly is different about them. I get the feeling the extra fuel pressure is related to emissions, so it might have no direct affect on the engine's running, but who knows...?

EDIT 2 - Had it confirmed today by a main stealer that an EEC2000 DEPOLL pump "isn't suitable". What that means is anybody's guess, but it's looking a lot like I'm gonna have to plump for the £198 main stealer price on the 1525C5 if I decide to get one

[stevieb]

Temptation got the better of me. Ebay had a genuine 1525C3 fuel pump for £60.00.

According to the parts guides this is for the ES9J4 engine, but was used in the old-shape 406 (D8). The seals and clamp are the same code as mine, so I'm hoping it's compatible, just an earlier spec. There's every likelihood it's the same as a 1525C5 anyway, as I know some other parts on the 406 were given new part nos. when Peugeot facelifted it despite being identical parts.

I can at least try it. My suspicion has lay with the fuel pump ever since I found such a change with the cleaned-up connector, and your findings just add weight to the argument as far as I can see Simon. Fingers crossed it's right