AX Diesel Problem

aps33 · Post by **aps33** » 22 Apr 2004, 15:50

I've got a problem with my Citroen AX 1.4 Diesel. Since I ran out of fuel a few weeks ago, it runs unevenly and surges, eventually cutting out and taking a few attempts to start again. The diesel usually has to be pumped through by hand to start it, and it does look like there is air in the pipes. I have tried bleeding the fuel from the screw above the air filter, but it seems ok. Any ideas?

jeremy · Post by **jeremy** » 22 Apr 2004, 16:18

Firstly replace the fuel filter. Its difficult to see that running out could cause much of a problem unless some water was drawn from the bottom of the tank and if you're lucky its in the filter which has done its job properly.
If thats ok it sounds as though air is getting in somewhere. You could try replacing the pipe feeding the injection pump with plastic and see if there is any air there with the engine running.
Jeremy

aps33 · Post by **aps33** » 23 Apr 2004, 13:04

Thanks, but I should have mentioned that i've changed the fuel filter, and the pipes from the filter to injector pump are transparent, and appear to have bubbles/air in the fuel. Any likely areas where it may be taking in air? Could the tank sender unit be faulty?

jeremy · Post by **jeremy** » 23 Apr 2004, 13:16

I don't think the sender unit or any other tank fittings except perhaps the outlet pipe junction will make any difference as they are all in the top of the tank and therefore there is an air gap betwen them and the fuel. I expect the outlet also comes from the top of the tank so an internal defect would probably stop the car altogether as an air leak here would probably prevent the fuel being drawn out at all.
Have you got steel pipes leading the fuel forward? These pipes will corrode and a pinhole will tend to let air in rather than fuel out. Same goes for any push on pipe fittings etc.
Plastic pipes themselves may also be a problem if thy are not new as they tend to ho hard and may not seal well.
Jeremy

davek-uk · Post by **davek-uk** » 23 Apr 2004, 14:07

If the engine was running well before you ran out of fuel, I'd suspect your problem is air left in the system rather than air suddenly being able to get it where it couldn't before.
To start off with make sure the system is properly bled. Did you bleed the system by loosening the injector unions after you ran out of fuel? Start off by pumping the primer and bleeding the fuel filter housing with the nipple on top. Then loosen the injectors and crank the engine. You'll gush some fuel over the engine but it is the best way to clear air out of the diesel pump. Reclamp the injector unions and try again. If it still misbehaves loosen the injector unions and do it again. You may have to do it a few times before all the air is cleared if you have a lot of air trapped in the system.
I've run out of diesel before and have had to do this before it would run - an embarrassing thing to have to do at the gas station.

jeremy · Post by **jeremy** » 23 Apr 2004, 14:51

Once the car is running it will purge air from the low pressure fuel circuit as it returns a substantial proportion of the fuel to the tank unused.
The high pressure circuit will generally clear itself of air as the normal bleeding instructions for it are to bleed injectors until it runs whereupon it will clear the others.
I suppose if you perpetually run it with minimal fuel some air could be drawn in as the fuel moves around in the tank. i would have thought that half a tank would eliminate this problem.
jeremy

aps33 · Post by **aps33** » 23 Apr 2004, 16:25

Thanks, thats given me a few ideas. I do usually run it with low fuel, so a decent tankfull could be a start. Will have a try over the weekend and post the results.

andycarter · Post by **andycarter** » 23 Apr 2004, 21:36

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">Thanks, but I should have mentioned that i've changed the fuel filter, and the pipes from the filter to injector pump are transparent, and appear to have bubbles/air in the fuel.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
I once had a *new* fuel filter that came with a faulty union and that was leaking air.

meexi · Post by **meexi** » 24 Apr 2004, 02:17

hi,
when i replaced the filter on mine and bleeded the system i found i was drawing air from somewhere. i found it was the filter housing there is a plug at the back which started leaking (you will need a small mirror to see it) i solve it by bypassing the complete housing with a big halfords fuel filter cant remember the number will check in the daylight.
meexi

Simon Canfer · Post by **Simon Canfer** » 28 Apr 2004, 02:04

I hope you've "bypassed the fuel filter" with a decent Diesel fuel filter; (or you can expect a fat bill for a new injection pump shortly...)
Aplologies if I've got the wrong end of the stick

Simon Canfer

meexi · Post by **meexi** » 28 Apr 2004, 03:10

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">I hope you've "bypassed the fuel filter" with a decent Diesel fuel filter; (or you can expect a fat bill for a new injection pump shortly...)<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
hi simon,
i was stuck at the time so had to go to my local garage who had a job lot of filters and i just used the biggest he had i change them every six months and it is due for a change soon i will look for something more suitable then.
meexi

aps33 · Post by **aps33** » 28 Apr 2004, 23:31

I went for the simple option and filled the tank up, and it cleared the problem. But, now i'm near empty again its starting to stutter. Of course the obvious solution is to keep the tank filled...

mikgram · Post by **mikgram** » 02 May 2004, 23:12

I`ve been driving diesel cars for the last eight years ,when my tank
gets around the last quarter I fill it right up ,apart from drawing
in air when you run out of fuel you draw all the sediment and #rap
into the fuel lines so when you start up again it can give problems.
if your fuel gauge is inaccurate zero the odometer when you fill up.
lecture over, if it was my car I`d take it into work at the weekend
and blow through the fuel lines with a air line.

Simon Canfer · Post by **Simon Canfer** » 05 May 2004, 03:30

I'm not saying running out of diesel is a good idea, but equally I'd say if you service the diesel filter regularly then there's no neeed to fill up until the warning light shows. I've been doing this for 15 years without problems. Indeed I now know my ZX does 60 miles after the fuel light comes on

At risk of teaching you grannies to suck eggs: The diesel filter is there to intercept water, and filter out crud down to a few microns (that's a few thousandths of a mm). So be careful when changing it!
I could believe that these days there's very little water in garage diesel tanks as fuel quality has improved and diesel sales increased; (not like when you had to fill up from the HGV diesel pump - IF the garage sold diesel!!)
Simon Canfer