Citroen C5 HDi engine dies

[Paul-R]

Hi all thanks for the tips.

Paul-R , I wonder if this safety thing which cuts feed to pump, if engine not started after a few seconds of ignition on, could be the problem

I wondered the same thing at the time. Back then I only had my multimeter to trace through the problem and I also only had the wiring diagram for the phase I car from a Haynes book so I was struggling a bit.

IIRC There seemed to be not enough voltage at the double relay setup, about 3v I think, and I couldn't work out why. The voltage drop was also constant reagrdless of the load which indicated a semiconductor junction, or more likely junctions, was dropping the voltage. The only thing I could think of was the ECU which is stuffed full of semicinductors but, as I said, I didn't have either a Lexia or wiring diagram to help.

The other thing that ties it in with the safety cut-out aspect was even this low voltage switched off after a few seconds.

TBH it's worked so well since then I just haven't had the inclination to upset it all. And anyway, it's my wife's runaround car and I'm sure she'd object If I said was going to reinstall a fault fault!

[hobblerian]

After my Dad's 2.2 HDI C5 went to Citroen for a new body computer (which went with a bang!) it then started to randomly stall and refuse to start. He had very similar symtoms to yours. Again opening and closing doors, locking and unlocking seemed to let it start again. It went back to the citroen garage and they eventually (after nearly a week at their garage) they said they found loose wires in the ignition circuit. This could be an area you might want to look into.

Ian

[wheeler]

Been reading this post & just though i'd add my tuppence worth about how the Bosch EDC15 HDi system works that may aid diagnosis of this fault.
The (factory fit transponder) imobiliser will not cause the engine to cut out, it only prevents it starting initially, the ECU stays unlocked as long as the ignition is on, If the key is not recognised you will get a flashing key light on the dash or imobiliser warning depending on which display is fitted.
The imobiliser system is completely passive & needs no input from the user apart from turning a correctly programed key in the ignition. ie locking & unlocking the door has no effect on the imobiliser.
The imobiliser does not cut power to the LP fuel pump , it just stops the injectors firing. There is no seperate fuel pump relay, it's an internal part of the under bonnet fusebox.
There is no fuel cut off/inertia switch on the C5, The airbag ECU deals with fuel cut off in an impact.

The electric in tank pump works as follows (this applys to just about every fairly modern fuel injected system with an electric fuel pump, both petrol & diesel) , The fuel pump can't run unless the engine is turning except when initially priming for a couple of seconds, The ECU then cuts it off again untill the engine starts cranking. design regulations mean the fuel pump must stop as soon as the engine stops turning. On this particular injection system this engine turning info comes from the crankshaft sensor. So if the engine is cutting out for a completely unrelated fault like a dodgy crank sensor it will also cut power to the FP.

On the Bosch HDi system With the engine running the FP does supply a constant pressure all the time & returns the excess to the tank.

You could run a switched fused feed to the FP for diagnostic purposes only.

[wheeler]

I wondered the same thing at the time. Back then I only had my multimeter to trace through the problem and I also only had the wiring diagram for the phase I car from a Haynes book so I was struggling a bit.

IIRC There seemed to be not enough voltage at the double relay setup, about 3v I think, and I couldn't work out why. The voltage drop was also constant reagrdless of the load which indicated a semiconductor junction, or more likely junctions, was dropping the voltage. The only thing I could think of was the ECU which is stuffed full of semicinductors but, as I said, I didn't have either a Lexia or wiring diagram to help.

The other thing that ties it in with the safety cut-out aspect was even this low voltage switched off after a few seconds.

TBH it's worked so well since then I just haven't had the inclination to upset it all. And anyway, it's my wife's runaround car and I'm sure she'd object If I said was going to reinstall a fault fault!

Did'nt you post about this a while back ? this is most likely caused by a poor connection at one of the two 23 pin round interconnectors behind the injection ECU, a more safer repair for this fault is to wire up a new battery feed to the input side of the double relay rather than direct to the FP meaning you keep the safety aspect of the fuel cut off system.

[Paul-R]

Didn't you post about this a while back?

I wasn't a member of this forum back when I had the original problem and posted on the old What Diesel web site. Unfortunately all that information has now gone.

I'm fairly sure that I've mentioned what I did in another post here in response to another post.

This is most likely caused by a poor connection at one of the two 23 pin round interconnectors behind the injection ECU, a more safer repair for this fault is to wire up a new battery feed to the input side of the double relay rather than direct to the FP meaning you keep the safety aspect of the fuel cut off system.

I unplugged and remade all the connectors I could find. I found evidence of slight corrosion on the pins of one of the three rectangular connectors going into the ECU (the sweat off a Peugeot workers brow falling in?) and tried to clean it as best I could together with copious doses of WD40-a-like.

When that failed to effect a cure I resorted to the rewiring as detailed as above.

[rodney]

hi I have this excact same problem on my 2002 c5 2.0 hdi , I changed fuel pump , cam senser and fuel rail and still the same , did anyone know the answer to this??,.