C5 2.0 Hdi difficult starting

[Peter.N.]

My car has progressed from the previous problem of intermittent poor starting to a permanant feature, it cranks for 5-10 seconds before it fires. Could it be air ingress or low rail pressure?

Peter

[citroenxm]

Hi Peter,

After she does fire, does she hunt a little on the revs for a moment??

If so, then fuel rail pressure sensor, the one facing down in the middle on the rail, behind the fuel filter house...

[Peter.N.]

Hi Paul

Hope you are beginning to feel better now. Once it starts it seems OK, before this problem began it started fine but hunted for about 15 seconds before settling down, doesn't do that now, once started its fine. I believe it has a new pressure sensor fitted by the previous owner.

Peter

[citroenxm]

Its pointing toward pressor sensor, the only other thing is the pressure regulator on the end of the pump!

Theres two choices here peter, get a pressure regulator for 175 quid on its own, OR take a chance on a whole pump which Ive now started seeing for 40 quid complete upwards...

My cutting out problem on my Xantia is pointing towards a pump, so I shall be getting one when funds allow.

[Peter.N.]

That's nearly as much as I paid for the car Will the Lexia help - if I can work out how to use it?

Peter

[citroenxm]

Yes peter.. because you should be able to goto the live parameters and watch the fuel rail pressure build as you spin the engine .. i had this issue with a xantia hdi.. the rail pressure sensor was dickie...

[Peter.N.]

I will try to work out how to do that, thanks Paul.

[RichardW]

Peter

Given your other thread about difficult hot starting, you may have a broken injector causing high leak off rate - you can check this with a pop bottle and a bit of hose - route the leak off into the bottle from each injector in turn (or all 4 at one go if you've got 4 bottles!) and run the engine for a few minutes to check if any leak significantly more than others. ECU needs to see 120 bar on the rail before it will fire the injectors, and it should be rock steady at 297 bar at idle, rising to 1500 bar at WOT under load

[Peter.N.]

I have heard about that Richard but it wasn't always difficult to start when hot only occaisionally, now its difficult to start hot or cold. Thanks for those figures.

There used to be dire warnings about fuel pressure on the old Perkins engines I used to run, it was ....2500 psi

Peter

[citroenxm]

Peter

Given your other thread about difficult hot starting, you may have a broken injector causing high leak off rate - you can check this with a pop bottle and a bit of hose - route the leak off into the bottle from each injector in turn (or all 4 at one go if you've got 4 bottles!) and run the engine for a few minutes to check if any leak significantly more than others. ECU needs to see 120 bar on the rail before it will fire the injectors, and it should be rock steady at 297 bar at idle, rising to 1500 bar at WOT under load

Thats intersting about the Idle pressure.

My Xantias has NEVER been rock solid at idle, even with another sensor! She starts and stops fine.. Just the cutting out. But I do now beleve its the pump!

As for peters car, Im sticking with - firstly rail pressure sensor to start with...

Peter, the pressure sensor has an auto sealing on it, when you remove it, it WILL NOT drain or loose any fuel. Why not try a swap over experiament. The 406 is working, so swap them over and see if the problem moves or stays, you will have an idea then!

[Peter.N.]

Good thinking batman - I will give that a try, when it stops raining.