Xantia Problem

integrale · Post by **integrale** » 25 Feb 2004, 14:03

Well I was looking to sell my xantia but now it's developed a fault overnight.
When the engine is at normal running temp, and you are doing approx 68mph which is 3000 rpm it is fine but if you accelerate any more afer a minute or so the engine coughs. This also happens if you floor the accelerator, but not immediately, there is some delay. When it happens the engine coughs once, maybe twice then is fine if you drive steadily again.
Anyone got any ideas what this might be? The car starts from cold and hot perfectly and idles fine cold or hot and drives absolutely normally.
The car is a 1998 1.8i 16v sensation 5door hatch with 85k on the clock.
Thanks in advance.

JamesQB · Post by **JamesQB** » 25 Feb 2004, 18:06

If anything was stopping the fuel coming through in the quantity necessary for that speed and RPM, I wonder if it'd cause the problem you describe as the fuel amount becomes too low. It may only happen after a minute or so as any excess fuel/pressure is being consumed until then and the starvation then comes into play?
Not my area of expertise but just an idea. Perhaps low fuel pressure from the pump or a dirty fuel filter, injectors or pipe...
Had a problem similar to yours with my Clio when on the motorway (only time I go fast...) so I replaced the fuel filter straight away since I'd had the car a while and never done it. Don't know if it cured the problem,mind, cos I never went on the motorway again after that as I had no need to, but I opened the old one and it was black and gungy inside so needed doing.
James

ActivaV6uk · Post by **ActivaV6uk** » 25 Feb 2004, 19:27

Its either the filter of fuel pump I'd think its the filter over every thing else. The only other thing i can think of is air is getting into the fule lines this happend when the lines are corroded.
Andy

integrale · Post by **integrale** » 26 Feb 2004, 22:46

thanks for the reply's! it seems to happen no matter how much fuel is in the car, but it doesn't do it unless i get it over 3000 rpm (like on the motorway)
i'm going to get a filter tomorrow and have a go at changing it.
Am I right in thinking that it is at the back of the car? had a quick look underneath and can't spot it.
Can someone point me to some pics or a diagram?
thanks

tomsheppard · Post by **tomsheppard** » 26 Feb 2004, 22:55

You might also check to see if you have a vented fuel cap and if so that it still is.

JamesQB · Post by **JamesQB** » 27 Feb 2004, 01:47

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by integrale</i>

Am I right in thinking that it is at the back of the car? had a quick look underneath and can't spot it.
Can someone point me to some pics or a diagram?
thanks
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
Yep, it's at the back of the car in a recess on the right-hand side of the fuel tank and clamped into place, they can be hard to spot though and it may be covered in lots of dirt and muck making it blend into the underbody. Should be a metal canister. Make sure arrow on new filter points towards hose leading to engine compartment and buy some jubilee clips when you get the new filter to put in place of the crimped clips holding the pipes on.
Might need to put car in highest setting to get access or jack up the rear, either way you'll need to support it securely with axle stands to avoid getting squished, which I've heard isn't much fun.
Good luck,
James

integrale · Post by **integrale** » 27 Feb 2004, 01:47

good point tom, will check in the morning. does it make a difference if the cap is vented and blocked? (explain as i'm dumb!)
EDIT: thanks for that james, very helpful!

noz · Post by **noz** » 27 Feb 2004, 01:55

integrale,
as you use petrol from the tank you need to replace the consumed fuel with air otherwise your tank will collapse with the vacuum. You'd get the same effect as sucking the air out of a plastic milk carton.
A vented cap allows air to pass in but does not allow the fumes to pass out.
If the vent isn't working a partial vacuum can be drawn in the tank and the pump will find it progressively harder to draw the required amount of fuel out of the tank. Of course the faster you are travelling the more fuel you have to draw form the tank.
The vent isn't always inthe cap. Maybe another Xantia owner can oblige with the whereabouts of the Xantia vent.
cheers
noz

integrale · Post by **integrale** » 27 Feb 2004, 13:39

Thanks for that explanation noz! Had a look for a vent in the cap and there doesn't appear to be one as the cap looks sealed. What I did notice though is a little green button at about 7 oclock next to the fuel cap and it seems to be spring loaded. When you put the cap back on and screw it down, it seems to press the button down a little bit but not right down. Could this be some sort of valve that acts as a vent, and maybe the filler cap is not pushing it down enough to open the vent?

JamesQB · Post by **JamesQB** » 27 Feb 2004, 21:33

The cap isn't vented, but there is a vent pipe that goes to the fuel tank itself. Where this pipe goes to, I don't know, perhaps it goes to that little green button that's pushed down by the cap if it is a valve. I've got a Xantia 1.8 16V and just checked the little green button and the cap only pushes it down a tiny bit when it's fully screwed down, so I'd assume that's normal.
I suppose you could try checking for a substantial vaccuum by revving the car to around 3000 revs and while doing that, have someone quickly unscrew the cap and listen for the noise of air rushing in, if such a thing could be heard over the engine noise. Otherwise it may be an idea, while under the car to change the fuel filter, to follow the hoses leading from the fuel tank until you find one that seems to be the vent hose and then check it's okay and see where it goes to and check the valve if there is one. Unfortunately, I can't find the info on which hose it is and where it goes to from the 'Aches and Pains' Haynes manual.
James