Xantia 1.9td air ingress question ...

[superloopy]

My 1995 td wont start without much cranking and foot to the floor. Usually starts first turn so ... air? I've changed leak off pipes, no go. Next on the list is fuel filter housing (replace) and pipe to primer bulb (replace wuth clear and new priming bulb ). Couple of questions, what's the diameter of pipe/spigot and, i'm assuming that the fuel filter housing just unbolts when its been emptied, yes? Anyone any unforeseen 'hurdles' to add? After all of this then i may take a look at glowplugs (i've changed the easy three without any difference so am guessing that its not the main problem). Other than not being able to run the car on the road, she's fine. All street legal but all i need is POWER!

[white exec]

Have you checked out the glow-plug relay, for dirty external and internal contacts?
If you can measure the current being drawn by the GPs, all four together should pull at least 50A.
Listed BERU GN909 are rated at 14A each at 11v.

[CitroJim]

Mike, yes, the fuel filter housing just unbolts. You'll see a bolt head in the bottom once you've removed the filter element...

No hurdles... All you say is good...

Prime the pump before starting afterward. Pump the primer until you can see fuel flowing back down the return line. The one the leakoff pipes connect to.

Also, I know you've replaced the leakoffs but have you also replaced the blind end cap on the last injector? I ask as these have a propensity to split and cause a lot of trouble. Replace it if in any doubt with a piece of normal leakoff pipe doubled up over itself and cable-tied tightly together..

The pipes are, I think, 8mm ID

[MikeT]

What's the exhaust like when it starts? Does it idle smoothly too?
It should have no problem starting on three good glow plugs.
btw, your right foot has no influence on starting, the pump governor has full control while cranking.

[superloopy]

Thanks all.
I've been out taking a look and ONCE she starts she idles ok but after about a minute the revs drop off and she stalls violently. I restarted and cranked the primer bulb just at the point of stall and she's alive again so i'm guessing that my problem is somewhere at the fuel filter / housing end? The pump itself makes a tapping/sucking noise just as the revs fall away which i'm attributing to fuel starvation maybe. So ... glowplug needs doing although i think i'll swap out the filter housing after having inspected the filter end of things. Does the primer bulb soften when the car is running given that its supposed to have a non return valve? My bulb goes 'semi hard' then almost immediately loses pressure, is this ok? Think i'll swap that out as well, must be a tenner well spent. Any ideas, keep them coming ...

[Hell Razor5543]

It may not be air getting into the fuel system, but (as you suggested) the engine being starved of fuel. There are microbes that grow and thrive in diesel, and over time a thick brown sludge builds up on the fuel pickup/level sensor on the fuel tank. Although I have not seen this for myself I have seen photos on this forum. If you pop up the rear seat you should see a black cover. Under this cover is where you can access the fuel pickup. Make sure to tie a long piece of string to the connector (as, if it drops out of the way it is supposed to be very difficult to get hold of it again), and also only do this when the tank is half full or less.

[CitroJim]

James, that's excellent You raise a good point... Well done for spotting something otherwise easily overlooked!

I've seen it and it's incredible... So yes, this must be checked as I agree, it does sound exactly like fuel starvation, especially given the pump noise...

It'll also cause hard starting too as the pump will struggle to build transfer pressure...

[superloopy]

So what exactly am i looking for? Wouldnt air in the filter housing also prevent it fuelling? Just wondering which end to fettle first? This all started gradually, the car was in use so i'm doubting the microbe theory. Starting became harder so i suspected glowplugs changing three. Made a slight difference but it then became really bad hence the air theory. The primer bulb ... should it remain hard after switchoff gradually softening? Mine goes soft immediatel even when engine is idling. Pumping it up restores revs ...

[Hell Razor5543]

I would STILL check the in tank filter/pickup.

[MikeT]

The primer bulb is just an inline manual aid and only works to draw fuel from tank and force it through where any air may have been introduced, such as when running out of fuel or changing the flter etc. When the engine is running, the pump is drawing fuel from the tank, creating a vacuum so the primer bulb will be soft.

If you find squeezing the primer when the engine is idling "restores revs", it indicates the pump is struggling to create adequate pressure at idle. This can be caused by fuel restrictions and/or air leaks.

[white exec]

If a Purflux filter like this one, there is a micro-fine gauze filter under the output banjo bolt.
Remove the whole filter, remove bowl and element, and relevant parts are in the head.
If dissembling, essential that you make a sketch of the bits you take out - must go back in exactly the same order/orientation, especially the tiny one-way/non-return valves.

Couple of other things:
- If tank venting isn't working, a vacuum can build up there.
- Plastic tanks on many PSA diesel cars . . . with age, bottom of tank can get unhelpfully close to the pick-up pipe, especially if the tank if lightly loaded with a small amount of fuel . . . any vacuum can make this worse.
Known occasional issue on XM.

[superloopy]

This has confused me ... where exactly on the filter housing would the gauze filter be? This is a mk1 1.9TD and i cant see where this would be. Changed filter a good few times and never seen a gauze microfilter. I'm going to check a few part numbers on service.citroen tonite, see if i can get pukka swapin parts.

[white exec]

Sorry if I confused. Likely your filter head isn't like this (photo added above). Ignore if not relevant.

[Hell Razor5543]

I have found the thread in question;

https://www.frenchcarforum.co.uk/forum/ ... 0&p=279995

[superloopy]

You're right Chris .... mine looks nothing like that