Xantia Hesitation

[froglet]

Hi All,
Have spent many months viewing this Forum and have had solutions, however ...
The age-old puzzle of Xantia hesitation.
Have seen air in the feed lines and have removed it. Have bled the system at the bleed valve several times, and at the injectors. Some limited success for some limited time!
The problem started with hesitation etc, cutting out at junctions. Did the obvious (to me) – read these forums.
Car stutters at speed, cuts out if revs drop below 1200 regardless of road speed - which can be embarrassing. Acceleration is great but easing-off gives problems – ‘the hesitation’.
Have good pressure at hand primer it pumps hard but soon goes soft. When running, has only occasional small air bubbles in lines but if it cuts out there are more air bubbles going back to filter!
Have a strange wiring configuration at lift pump - 2 greens, 1 white, 1 red. Tester shows 5+ volts between greens, nothing at any other configuration. Testing the other configurations shorts-out fuel gauge readings. Haynes BoL surprisingly useless for fuel system wiring (have had success with Lagunas/2CV’s/Dyanes etc) and this Forum has provided unobtainable wiring diagrams (no name, no pack drill).
Don't say Lexia (in France). Don't say Main Dealer diagnostic (for same reason), you need a mortgage just to get them to open the garage doors!
If there is a genuine genius out there, please help before I clean the windscreen wipers!! Cannot carry-on over-revving at junctions and stopping (just) on handbrake!! One day a little old lady will have a close-up of my bumper!
Am becoming a tourist attraction in my own right.
As an afterthought - all fuses OK. Auxiliary drive belt changed but many months before present problem, Air filter changed, Fuel filter changed (and bled – it was half full of fuel), Oil filter changed. Have had inlet manifold off and removed 15 years of oily gunge - small improvement for @ 20 miles. Have removed and cleaned sensors (that are visible).
When testing(?) fuel lift pump there is NO noise for 3 or for 5 seconds, just no noise at all, ignition on, code in, cranking or not.
With solutions please bear in mind prices over here are at least 2x that in UK (rip-off Britain I think not, now) but it is only raining slightly!!
This car is a '97 Mk 1 Xantia 2.1 TD VSX, with a Lucas Epic and @ half a tank of very expensive diesel. Never mistakenly filled with petrol, or bio-fuels but in Spain recently did put higher grade diesel in tank - had to get home!
HELPPPppppp!!!!!
As a second afterthought, today when it cut out (20mph, 1600rpm) the fuel gauge dropped to zero and low-fuel warning light came on. There was plenty of fuel and when it eventually re-started the fuel gauge slowly rose!
If I have to keep the revs so high, can it be the pedal potentiometer? If so, how do I access it?
AND … what is ‘limp home mode’? mine either stops or goes again after sufficient cranks, until it decides it’s had enough.
There is a cheapish C5 for sale locally, will its parts fit? – not the wipers, mine are clean.

[KennyW]

Froglet,

Have good pressure at hand primer it pumps hard but soon goes soft.

It still as air coming into the system because of the above quote.

Have you checked the fuel return to tank as air leaks there can cause this.

I'm sure once Jim (citrojim) looks at this he''ll advise further.

[6speedmanual]

Hi
I had this problem on my 2.1.

Rplaced the fuel feed pipe from the priming bulb to the fuel filter / separator pot.
Used normal rubber fuel pipe and jubilee clips as this pipe is not running under pressure.

Hope this helps.

Peter

[red_dwarfers]

If you have air bubbles you should sort that out before tinkering around with other things or you will be likely chasing your own tail. Air bubbles can't be generated by electronics but they could cause the electronics to get confused.

The best way is to logically work through all the pipes then move onto the priming bulb and fuel filter housing. It's not unknown for those two to go holey. My 2.1 EPIC XM at the moment has a problem with fuel running back to the tank if I park on the level or nose up but I've not got around to fixing it.

If the pipe swapping doesn't solve it and you can borrow known working parts be careful as the 2.1 uses different size fuel pipe than the 1.9 so the priming bulb is different.

I hate to say it but the EPIC isn't without it's faults, I think there has been one or two cases on here of air ingress, I could be getting confused with Bosch's though.

[froglet]

Many thanks for suggestions so far.
Have traced fuel lines back to tank - no leaks. Also opened tank to examine lift pump - now I know it doesn't have one, only a sender unit!! Duhhh, where are those wipers?
Have managed to watch fuel lines whilst engine running (rare occurrence). There is no air appearing in the feed line to the filter.
Some very small bubbles go from filter to injection pump BUT ... when it stalls there are globules of air going back from the injection pump to the filter.
Have found other clues throughout this forum and bells have rung regarding recent change of fuel filter.
There was an increasing but slight problem before I changed the filter, now it is worse.
Is this pointing towards a u/s filter-housing/seals. Can't buy Hermatite over here, is there an alternative I can use to double seal the seals?
As an added afterthought, and I do have many of them, the potentiometer on the end of the 'go' pedal doesn't seem to do anything. I can rev with the pedal and see movement of the small arm coming out of the pot but if I just move the small arm nothing happens!
Excuse me, I can see a spot on my L/H wiper;

[froglet]

SUCCESS!!!!
It was the banjo union from the injector pump(Epic);
Had tried everything else including PTFE tape on all line joints - tank, pipes, bleed nipple etc etc. Then doubled up with gaffer tape. It's almost impossible to get parts over here without going to Main Dealers, who give you an appointment.
So, obviously(?) the air going back to the filter and on to the hand primer was getting in at the banjo - easy when you know how!
Now, on to the n/s outer CV boot, oh and the o/s steering rack boot!
Thanks for all suggestions, it kept my mind focussed while the engine management light came on at less than 2500 revs

[froglet]

Oh Dear!!!! Not so easy after all. Did seem to solve the problem for a while but it gradually returned. Have checked all lines and changed grenade - various short term success. Still the same - when it cuts out there is air going back to the filter. Re-sealed all lines from filter to pump - some success, then back to normal. Removed filter casing and pipe, re-sealed base and joints to/from it using mastic - some success, for a while. After every attempt it improves then returns to no lower-revs tick-over. Still cutting out at low revs but now back down to @1500 rpm before turning itself off. Have even found French equivalent of Hylomar - some success for some time. Usually about 10 miles before the usual happens at junctions, though at other times sometimes it does tick-over.
Surrendered today to main dealer to undo hub-retaining nut to change outer CV boot (been saving). He now says it is the Epic. Can be done cheap = 3,346€. That is not a mis-type!!! Please excuse the tears in my eyes.
Problem/suspicion for me is; if it is the pump why does it go like stink when it is going, why does it stop when on low revs? Surely if it is the pump it wouldn't work at any time?
So, been back to drawing board so many times I've got a loyalty card. Now it's either fix the pump or it's the great scrapyard in the sky at only 101,000 miles. Surely not. Anybody out there got any helpful suggestions apart from my last, please help a girl in distress (the car that is).
Keep thinking of the 2CV I once had, but then that didn't like starting in damp weather!

[Peter.N.]

If possible try parking the car facing down a very steep hill so the tank is above the engine, the fuel system is then slightly pressurised so your air leak should show up as a fuel leak.

Peter

[Old-Guy]

I suspect you are chasing your tail dealing with symptoms of a basic fault that you can't resolve. So, without casting any aspertions on your intelligence or knowledge:

Design Facts -

• The low-pressure (LP) fuel system between injection pump (Bosch or EPIC) and tank is under partial vacuum (the pump both sucks fuel from the tank and delivers high pressure fuel, in timed and measured squirts, to the injectors).
  The filter is at the highest point of the LP fuel system after the priming pump, so any air in the LP side tends to run back to the filter when the engine stops.
  The leak-off pipes from the injectors join the return-to-tank pipe at the pump.
  The fuel return to the tank goes slightly down from the pump before going up and over the engine (so air in the return tends to go back through the pump when it's not working).
  Air, being much less dense and viscous than diesel, will get in where diesel won't leak out under pressure from the priming bulb.
  The leak-off pipes, particularly the blank-off on the gearbox end, are a common source of air leaks and replacement pipes often don't last too long.

Conclusions: You've fixed a series of apparent air leaks and each time, another air leak appears. So something seems to be causing new air leaks - i.e. the next weakest spot each time. All the evidence points to a constriction in the LP fuel system, such that when the engine is running the LP system is under much lower pressure (greater partial vacuum) than designed: the most likely candidate is the tank breather blocked (any signs of an in-rush of air when the filler cap is removed after a run?).

Solutions:
Replace the leak-off pipes if you haven't already done so as the stream of bubbles as soon as you switch off indicates that air is getting in via the pump.
Check the entire LP system from the filler cap to the filter for constrictions; starting with the tank breather pipe (it joins the filler neck near the top and runs down behind the wheel arch liner where the end can get blocked with mud), tank filler/breather neck moulding, tank filter (the increase in bio may have loosened ancient muck in the tank), kinked/squashed pipes. I'll post a drawing later.

Best of Luck

[froglet]

Many thanks for the input 'Old Guy' it's good to get a fresh perspective.
Haven't changed the leak off pipes yet as these seemed ok but am I fooling myself - just because I don't see leaks there, it doesn't mean they're not!!
Look forward to the drawings, that would be really helpful and will follow your advice re the above. Whilst at it, how do I get the plastic protection off the under-body fuel pipes where they disappear into the engine bay along the bulkhead? Have done the rest of the line but is there a secret to this bit?
Once again, many thanks for all your info.

[Old-Guy]

Don't know how the plastic protector comes off, but I wouldn't worry about this until you've checked the tank breather pipe (you should be able to blow up it with the fuel cap off) - by far the most likely candidate. Your experience with the full tank fits this perfectly: with a blocked breather, the (plastic) fuel tank will slightly collapse under suction from the pump which increasingly struggles to suck enough fuel.

[taffy]

Have u tried removing fuel cap incase its blocked?could put pressure on a leak

[taffy]

Only other thing I can say on theses symptoms is wat happened to my mates 1.9 bosch...put heating oil in it and dried The pump out...bit of oil in The fuel helped but he got rid not long after it was too hard to drive...I hope its not ur problem thou...

[Old-Guy]

Drawing of tank components here

[froglet]

A belated many thanks to all for suggestions. During a visit to another Main Dealer for tyres (it's how they do it here) got into conversation with the mechanic. Refused to sell me leak-off pipes - it the pump he said, tapping it in Gallic fashion and suggesting 2950 euros. After coming down off the ceiling the conversation continued along the lines of the breather.
No, he said, there is a gate to only allow one-way relief? Don't go there, it was the way I wanted however ... it did explain the feeling of rupture when I tried to blow up the breather pipe. So, taking all postings into account and unable to get around the breather problem, I drilled a small hole (1.5mm) into the filler cap with remarkably little improvement, or none. Back to the leak-offs.
Many thanks to eBay I did manage to get some small bore fuel pipe, replaced the leak-off pipes etc and - success. It has now gone for 3000 miles through all sorts of high temperatures (44° one day!!) and has only just started to deteriorate. At £5 for leak-off pipes I can afford to do this job 600 times and still be quids in. Many thanks again to all, especially old-guy. Right again!