Xantia HDi 90 won't start

[CitroenCrazy]

Anyone any thoughts on my mate John's Xantia HDi 90, please ?

Symptoms:
Driving along one day, it seemed to suffer fuel starvation & coasted to a halt.
John assumed low pressure (in tank) pump, and swapped it - by the side of the road - with the spare one he had with him (as you do !)
Car starts & runs ok for a day or two, until the same thing happens again.

It's currently having a full-on sulk and won't start.

When the ignition is switched on, the LP pump runs to build pressure and then stops; it can be heard running when cranking.
Fuel filter has been changed
There's evident fuel flow if you slacken off the fuel supply to the HP pump.
So, LP side of the fuel system seems ok.


Slacken off one of the HP unions on the fuel rail and look for fuel weeping when cranking - none evident, stays dry.

Squirt some easy start into the intake manifold while cranking and the engine will start and run - briefly and "crackily" on the vapour .

I've connected my Lexia, cleared previous faults and then re-read the ECU after the "run on Easy Start" episode. Only one fault came up - no pressure detected in HP fuel supply.

So, yes, it all points to a problem with the injection pump, but since it has run properly since the fault first occurred, we tend to think it's not mechanical failure of the pump itself.

Could it be electrical ? Not sure whether the ECU can inhibit the pump for some reason ??

All advice gratefully received.

Thanks

[Hell Razor5543]

I don't know much about the 90HP HDi, but I do know (from what I have read on the forum) that if there is insufficient pressure on the fuel line the ECU detects this and won't trigger the injectors. IIRC there needs to be 200bar on the fuel rail.

When was the fuel filter last changed?

I wonder how the immobiliser system works, or if it is relevant in this case?

[Old-Guy]

I'd suspect a lack of fuel from tank. Just because the LP pump runs, it doesn't mean it's actually pumping sufficient flow (or any at all). Blocked tank breather? Tank filter? Lump of cr4p in fuel line.

[Hell Razor5543]

I'd suspect a lack of fuel from tank. Just because the LP pump runs, it doesn't mean it's actually pumping sufficient flow (or any at all). Blocked tank breather? Tank filter? Lump of cr4p in fuel line.

Somebody in the last few weeks had a blockage in a fuel line (IIRC a flake of paint), and when he blew it clear the car started running properly;

http://www.frenchcarforum.co.uk/forum/v ... 33#p408433" onclick="window.open(this.href);return false;

[Peter.N.]

The regulator on the HP pump has a filter in it, these can block and be impossible to clear, some don't have a filter, that being the case you can grind the end off and allow full fuel flow. The one on my C5 is now running perfectly without the filter. The pressure regulator is held on to the pump with two screws, you will see the filter as soon as you pull it out.

Peter

[isisalar]

Hi Peter, sounds like this filter in the regulator is something that should be checked and possibly cleaned.
Anyone got any further info on location, method etc.?
Likewise with the tank filter, does this have a filter that can be cleaned or replaced?
I've noticed that a lot of the starting/running issues with HDI's seem to be related to these items and I'd rather prevent trouble than have it at the moment.
Cheers
Paul

[Peter.N.]

The pump pressure regulator is on the back of the pump nearest you when you look at it, its held on with two screws maybe torx or allen, there is also a plug to remove. When you pull it out you will see what looks like a metal tube on the end of it, this is actually the filter but the holes are so small you cant see them, mine had iron filings sticking out of it, if you can find some way of cleaning it good but I had to remove mine. The easiest way of dealing with it is just to grind the end off, making sure you get all the loose metal out.

You can probably get a secondhand regulator one from ebay for not to much money.

Peter

http://www.ebay.co.uk/itm/0281002493-PU ... 2c77b818bb" onclick="window.open(this.href);return false;

[citroenxm]

On the HDi 8v engines.. Fuel WILL ALWAYS flow to the injectors IF ITS CLEAR TO DO so and IF the fuel Pump on the engine works correctly!

Undo one of the unions to the injectors and spin the engine over!! It should JUST LIKE an older TD IDI XUD engine STILL spew fuel out at the injector connection...

IF there IS fuel there, then its an electronic problem, OR as said lack of pressure, in which case my first suspect will be the pressure regulator on the end (OR side ) of the engine pump...

[CitroenCrazy]

Many thanks all for your input, it's always good to see a consensus from the experts

I've passed the advice on to John; now he just needs to get busy......

[BX]

Use the lexia to read the fuel rail pressure. A blocked filter on the regulator will not prevent pressure from building. The symptoms of a blocked filter regulator are that the car starts but will stop without warning usually when driving at moderate rpm. the car can be restarted after resting for a minute or two only for events to repeat. If you have a regulator WITHOUT a filter dirt can prevent the valve in the regulator from closing fully. pressure will not build and the car will not start.

[citroenxm]

Use the lexia to read the fuel rail pressure. A blocked filter on the regulator will not prevent pressure from building. The symptoms of a blocked filter regulator are that the car starts but will stop without warning usually when driving at moderate rpm. the car can be restarted after resting for a minute or two only for events to repeat. If you have a regulator WITHOUT a filter dirt can prevent the valve in the regulator from closing fully. pressure will not build and the car will not start.

DONT I know this very well!! I replacement regulator sorted this. Mine never failed to start, but anything over Half throttle and she would stop dead! But after a few seconds of coasting would start again. Thats why I mentioned the regulator on the pump in my post.

HOWEVER, A lexia reading wont always give you the correct rail pressure for a car thats not going to start because of the way the rail builds pressure and the delay in the reading out put! Ive had a car start with a rail pressure SHOWING 60 (is it bar) and running by 160 bar then settling to 300 or so bar at idle..