low fuel pressure at rail on 2000 Citroen synergie

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mikeb49
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low fuel pressure at rail on 2000 Citroen synergie

Post by mikeb49 »

Hi i have a 2000 Citroen synergie 2.0 hdi which has done 14000 miles and up untill recently has been very reliable.

about three weeks ago it cut out while my wife was driving it, she managed to restart it a couple of times but it eventually died.
the engine light was on and when the AA came out they said it was a low pressure fault at the rail?.
i have read several threads about what it may be and have passed these on to the garage who have now had it for two weeks!.
it will sometimes start and run fine for short periods, sometimes it starts and runs rough and stalls,sometimes wont start at all !.
amongst other things the garage bypassed the main fuel filter and it seemed fine,so they fitted a complete filter and housing which was ok for 7 short trips then the same problem!.
for the previouse few weeks before it broke down we noticed a strange whineing when starting up, it turned out to be the in tank pump [which had been replaced about 12 months before] i know that if this fails it can cause the fault that we have.
what i would like to know is should you be able to hear this in tank pump when you turn the ignition on but before you start engine, it's quite loud and sounds like a whine or a groan which lasts for about 5 seconds and then it cuts out, , i tried turning the ignition on and off several times in a row without starting the engine and it made a noise every time but you cant hear it once the engine starts.
i also own a peugoet 1.9td exspert which is similar and i cant hear the pump in this at all.
i'm wondering if the pump is working but not delivering enough pressure to the high pressure pump? how can i test this?.
we now have the car at home again, thats were it broke down so will need a tow back to garage.

any help or insight would be appretiated.
regards mike.
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Re: low fuel pressure at rail on 2000 Citroën synergie

Post by mirafioriman »

Sounds like there could be a fault with the low pressure pump. I would guess that there will be a specified pressure from it and you will need to test the fuel pressure in the fuel line before the high pressure pump.
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Re: low fuel pressure at rail on 2000 Citroën synergie

Post by myglaren »

Welcome Mike :welc:

Yes, you should hear the in-tank pump prime the system (if it has been dormant for a while).
Get someone to turn the ignition on but not start the car and listen close to the tank.
If it fails to operate a kick to the bottom offside of the tank can often give it a spurt of life but it won't last long.

One unfortunate side effect of the in-tank pump failing can be very fine swarf being fed through the fuel system.
This is generally trapped in the fuel filter but if it is suspected then it is advisable to remove the filter and housing completely and very thoroughly clean the housing to remove all evidence of this fine swarf. Even better, replace the housing.

The bad side effect is that if it finds its way into the high pressure pump it can destroy it.

I do hope that this is not what has happened in your case and that it can be remedied without drama.

It could also be a duff pressure sensor on the rail. There is a recent thread mentioning just that.
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Re: low fuel pressure at rail on 2000 Citroën synergie

Post by Peter.N. »

The 1.9td doesn't use an in tank pump.

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Re: low fuel pressure at rail on 2000 Citroën synergie

Post by myglaren »

Peter.N. wrote:The 1.9td doesn't use an in tank pump.

Peter
So much for that theory then :oops:
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Re: low fuel pressure at rail on 2000 Citroën synergie

Post by mirafioriman »

So how does the fuel get from the tank to the high pressure pump?
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Re: low fuel pressure at rail on 2000 Citroën synergie

Post by myglaren »

mirafioriman wrote:So how does the fuel get from the tank to the high pressure pump?
Either the high pressure pump has a low pressure stage or there is a primer bulb under the bonnet.
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Re: low fuel pressure at rail on 2000 Citroën synergie

Post by CitroJim »

mirafioriman wrote:So how does the fuel get from the tank to the high pressure pump?
It [the 1.9 XUD engine] has a mechanical van-type lift pump built into the injection pump.

This is why air in the fuel lines can be such a problem on the XUD engines. The pump has to draw all the way from tank to engine.

The primer and filter are before the lift pump...
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Re: low fuel pressure at rail on 2000 Citroën synergie

Post by mirafioriman »

That clears that up then but the original post said that the in tank pump was replaced 12 months ago?
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Re: low fuel pressure at rail on 2000 Citroën synergie

Post by myglaren »

mirafioriman wrote:That clears that up then but the original post said that the in tank pump was replaced 12 months ago?
Indeed it did!

Round and round in circles :(
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Re: low fuel pressure at rail on 2000 Citroën synergie

Post by CitroJim »

Right, sorry yes, I didn't realise the original questions had not been answered :oops:

Yes, you should hear the in-tank lift pump make a low, smooth hum as soon as you turn on the ignition. Unless you start up the pump will stop after five seconds.

If the pump sounds at all harsh, loud or jarring to the ears then it's dying... 12 months old or not.

Another cause of this is simply a duff sensor but if the pump is making anything other the a low, pleasant sounding hum then that's the most likely fault.

The garage did a very silly thing in bypassing the filter. It's there to protect the very high precision hp hump and injectors which can be damaged by dirt, especially of the aforementioned metallic particles that may have got in the fuel line from a bad lift pump in the process of breaking up. You have to take extreme care just renewing the element on an HDi.
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Re: low fuel pressure at rail on 2000 Citroën synergie

Post by BX »

Sounds like a faulty high pressure regulator. The problem will actually be pressure going too high causing the ECU to halt the engine. After a short stop it can be restarted and runs fine until the next time. The regulator is fitted with a 5 micron filter which cannot be cleaned. This is finer than the fuel filter. After failure of the in tank pump, blockage of the regulator filter often occurs. There are 2 solutions
1. A new regulator. This is available from dealers & most autofactors
2. Break off the filter. Its purpose is to protect the regulator needle and seat. Many of the newer regulators do not have this filter fitted.
Removal of the regulator is simple. It is fixed to the back of the HP pump with 2 torx screws. Plug out the electrical connection, remove the screws and the regulator falls off. Take care not to loose the metal gasket.
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Re: low fuel pressure at rail on 2000 Citroën synergie

Post by DickieG »

Before spending money on new parts carry out a 'wiggle test' on the electric socket connectors on the fuel pump pressure regulator (end of the pump) and the fuel rail pressure sensor, ideally remove inspect and spray the contacts with electric contact cleaner. If that doesn't sort it clean around the fuel pump pressure regulator then remove it (two allen bolts) and check for debris around the probe, clean using paper towel and if you have a clean magnetic probe carefully place it into the open recess in the pump to remove metal debris then refit the pressure regulator. That might work, it did for me once on a Picasso HDi.
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Re: low fuel pressure at rail on 2000 Citroën synergie

Post by CitroJim »

Interesting stuff, especially that the pressure regulator does not necessarily have to be replaced.

Presumably if the pressure regulator is the cause then a Lexia will see a stored fault indicating this to be the case?

I can't help thinking the garage that bypassed the filter for a 'test' may have made this problem worse in doing so by allowing possibly more muck to get to the regulator.
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Re: low fuel pressure at rail on 2000 Citroën synergie

Post by mikeb49 »

Many thanks for all the replys i will pass the suggestions on, or maybe have a go at some myself.
will let you know the results.
mike.
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