Question on low pressure fuel pump Xantia HDI

[romik]

I have recently had a brakedown, couldn't get it started. About half hour prior to it I noticed there was a noise coming from behind somewhere lasting a few seconds and switching off. I told that to the AA guy and he bashed the fuel tank from underneath, that noise reappeared and engine started up. The garage later replaced the low presure fuel pump, yet that noise is still there b4 engine starts up. Any idea why that is?

[Lighty]

The fuel pump primes the system for about 3 or 4 seconds before the engine starts, it continues once running, but the engine noise covers it up to a degree.
I would imagine that you are just noticing it more after the breakdown.
Its when there is no noise you need to worry

[CitroJim]

As Lighty says, it is normal but should be just a low hum, hardly noticeable really unless you're listening to it.

If it's really loud than things are not good..

[romik]

The fuel pump primes the system for about 3 or 4 seconds before the engine starts, it continues once running, but the engine noise covers it up to a degree.
I would imagine that you are just noticing it more after the breakdown.
Its when there is no noise you need to worry

Ok so it's normal then, good. I could swear there was no noise before, I am always listening out for all sorts of noises.

[romik]

As Lighty says, it is normal but should be just a low hum, hardly noticeable really unless you're listening to it.

If it's really loud than things are not good..

What can it be then?

[CitroJim]

What can it be then?

Pump on the way home...

Some are a tad louder than others though..

[romik]

What can it be then?

Pump on the way home...

Some are a tad louder than others though..

Oh it's just been changed.

[Peter.N.]

The probable reason why you didn't hear it before is that previously the engine has always started and drowned it.

Peter

[romik]

The probable reason why you didn't hear it before is that previously the engine has always started and drowned it.

Peter

But noise takes place prior to starting engine. It seems likely that it's down to different brand of pump.

[CitroSwede]

Is it a vibrating sound?
Put your hand on the floor behind the seat and feel if you can feel vibrations.
If that is the case, it´s "just" a vibration that comes from a resonance in the fuel system.
It´s more annoying than harmful. I had these humming vibrations in my Xantia, and it drove me crazy.
But after i installed a fuel pressure regulator on the fuel line from the tank to the filter housing, it all disappeared.
Now it is absolutely quiet. That regulator were fitted on 2,0 HDI:s by Citroen and Peugeot, but only when the customers complained.

[Peter.N.]

The probable reason why you didn't hear it before is that previously the engine has always started and drowned it.

Peter

But noise takes place prior to starting engine. It seems likely that it's down to different brand of pump.

Ah right, my 406 starts immediatly you turn the key so I don't hear the pump.

Peter

[citroenxm]

You possibly Peter have NOT got a Tank lift pump..

If you have a Siemans Fuel system Im led to beleve the Siemans system does NOT have a lift pump in the tank as its built into the engine pump, like an old Roatry Pump...

Not seen a Siemans system setup at all yet

[Peter.N.]

I will have to check that Paul, I thought all the Peugeots had a lift pump, but I could be wrong - again.

Peter

[citroenxm]

its down to which fuel system it is peter... bosch needs a lift pump ah la xantias and c5s but the siemans system doesnt.. which ive heard isnt as good as bosch.. but i dont onow. . ive never seen or driven a siemans setup...

[RichardW]

You're right Paul - the Siemens system doesn't have an in-tank pump - it can be recognised from under the bonnet by the presence of a priming bulb similar to the old XUD ones. Some Xsaras are fitted with the Siemens system, but it didn't come in till 2002 or thereabouts, so all Xantias are Bosch.

Interestingly if the pump is making a lot of noise, it may not be the pump at fault.... there is a bi-metallic strip bypass valve in the fuel filter, and when this gets a bit old it can vibrate and make a right old racket. Although replacing the pump reduces the noise, replacing the fuel filter unit is the ultimate cure. Having said that the pump on mine can be noisy(*), and I've replaced the fuel filter (which has shut it up a lot, and removed a low down hum I used to get at idle).

* presumed original at 127k - certainly not changed in the 80k I've had it, and it's always been on the noisy side....!