Xantia let me down...fuel rail sensor?

[Chlorate]

Hello all, not a happy bunny this morning.

Driving to work on the A5, the car made a bit of a lurch and the engine management light came on, "oh globbits that's not good" I'm thinking. Engine still going ok, although felt a bit sluggish, "fuel starvation?" I'm thinking, "better try and nurse her to work", few hundred yards later the power plummeted off and eventually stalled and refused to start.

Car picked a heck of a place to do it, 2 lanes, no hard shoulder, no barrier and too far to push uphill to a layby. AA turned up with a flatbed to get the car and I to a safer location. AA roadside assistance chap turned up shortly after and had a quick once over, managed to start the car like normal (after a bit of a boost on the battery) car idled OK but was in limp mode. Plugged his diagnostic tool in which reported an issue with the fuel rail pressure sensor.
Dragged the car to a place called Diesel Diagnostics in Coventry and got the taxi to work.

Any guesses as to what's wrong?

Hopefully it's something as trivial as the sensor, or even a blocked fuel filter...
Had a peek under the bonnet, no obvious signs of leakage. I'm hoping that since the car started and Idled the pump and injectors are ok...

Alex

[jgra1]

shame Alex.,
my hdi showed it's hand last night...

aunti pollution warning and EM light.. car felt sluggish twice yesterday.. drove to work today and felt ok, light still on.. no lexia.
grr

[RichardW]

Could well be the LP fuel pump - fuel rail pressure sensors are pretty reliable - and it may well throw a fault code if the pressure drops because the low side pressure has dropped. You probably need a Lexia that can give live data though to see what the pressure's doing.

[Chlorate]

Quick update,

Rang up the garage, they confirm the problem is something to do with fuel rail pressure.
They did a leak-off test and the injectors look OK - I'm hoping this reads across to the injection pump too.

So with any luck something trivial has gone wonky on the low pressure side, so either of the filters or the lift pump perhaps.

Still not going to have it until tomorrow...

Glad it's payday next Friday.

Alex

[CitroJim]

A fault of this kind should be easily diagnosed with a Lexia. I hope the garage know what they're doing and don't go for a 'try this bit' in vain hope..

Shame it's with the garage as a simple test of the lift pump is to see if you can hear it running when you first turn on the ignition.

Problem is, there is a myriad number of causes and if the garage can't run a diagnostic they could be working a bit blind...

[DickieG]

Before spending loads of money on expensive tests or replacing parts has a 'wiggle test' been carried out on the fuel rail pressure sensor and fuel pump pressure sensor? If not remove them, give the contacts as much as a clean as possible, spray with electric contact cleaner then reassemble together with a wiggle, worked a treat on a Picasso HDi I was given the task of sorting out after it had been in a garage having numerous parts replaced to no avail.

[Chlorate]

Hello again,
Got a call just before I left work, they said they couldn't find anything wrong with the low pressure side and are beginning to suspect the injectors
I'm not convinced, I'm having a hard time seeing why knackered injectors would cause a car to go from running fine to dying completely in a matter of minutes, then some time later starting and idling fine again...

My thoughts on the matter would be an intermittent fault on the lift pump side - maybe it cut out fuel pressure dropped, ecu activated limp mode, engine slowly but surely cuts out as the injection pump isn't being fed. Then at some other time the lift pump comes back to life and hey presto, engine starts and idles as usual but limp mode persists.

I'll definitely mention the wiggle test when I give them a call tomorrow morning.

As for the rest of my day....got a lift back home from someone at work f*cking house key is still in the car...

Alex

edit: Further thoughts on the matter:
If the injectors were so badly worn that the fuel rail would depressurise to the point of stalling the car (which is what the garage thinks), I would seriously doubt that the car would start at all let alone start on the 4th crank and have a steady idle which was seen when the AA chap had a go. And why it would happen so suddenly is another matter.

[CitroJim]

It won't be the injectors Alex. Sounds like they're clutching at straws.

The rail pressure sensor itself is a good candidate if the wiggle test doesn't work. I believe these have been known to fail in the past.

[Chlorate]

That's a weight off my mind there Jim, I wish she broke down on the way home really didn't want to leave it with someone before asking FCF.

Oh well, live and learn.

[Chlorate]

"There's nothing wrong with the sensor" he says "the diagnostic says so"...In other words he hasn't looked at it and would rather sting me for new injectors.

I've instructed him to go ahead with the injector test, give me a call to talk about it, and if there's nothing obviously wrong with them (although I'd wager he'd say there was anyway) stick them back in and clear the fault off and I'll take it home (running the gauntlet of course, since nothing has actually been fixed).

I can see the purchase of a Lexia coming up...

[Chris570]

*ahem* on the xantia hdi the engine will run without the sensor, it has the eml light on but will run.

Also..... the diag machine must be able to give a proper set of fault codes or failing that run a lexia accross it. Injectors are unlikely considering it ran again.

[citroenxm]

I had this on a W plater... It was a dodgy fuel rail sensor, the one that sticks DOWNWARDS out the bottom of the rail..

Swapped it, problem went away... Injectors rarely give issues and I dont think they would have a car stop.. and secondly if one did go down my guess is the car would misfire and run on three... you most certainly would NOT get all three go down together unless theres a real issue like veggie oil in it...

[Chlorate]

Got the Xantia back,

It was the sensor after all, the silly conversation I had this morning was down to them somehow getting my car with a Xsara Picasso (with knackered injectors) they also had in

[citroenxm]

nice one.. never a serious issue with these superb 8v units.

i doubt that Picasso even has duff injectors unless it does have serious neglect...