C4 B7 not starting

[mostcho]

I have C4 B7 1.6eHDI 2014. It is not driven every day but once a week. It was running noraml until one day the battery was dead. I recharged it and everything was back to normal. A few weeks later i tried to start the car again and the engine was cranking but it was not starting. Checked the battery it was OK. I hooked it to another car to try to start it and it didnt start. Checked the fuses and were OK. Connected it to Diagbox and there were lot of errors but non of them were leading to probable cause but only to dead battery. Tried another battery and again nothing. Tried to manualy pump fuel with the button on the filter and it was hard as rock. Changed the fiel filter. Filled up the system with fuel again with the button and nothing again. Changed BSM, nothing again. Checked engine RPM when crancing - 280. Checked pump preasure ~300 bars. No fiel on the injectors. There was 12v on the pump and there was nothing on the presure valve BUT when i gave 12v from the battery to the presure valve i felt some clicking inside. And after everything there are no mistakes in the BSM, BSI or ECU. What could be the issue? I tried searcing the net and talking to the AI friends and the AI was leading me to broken wire somewhere. Could it be ? I am out of ideas.

[Sloppysod]

Simple thought, is it's not the immobiliser messing things up, if I remember correctly the immobiliser does not stop crank, just the starting side of things.
There should be a related fault code .

[mostcho]

I tried both of the keys, changed batteries of the remote in case if something. But it is still not starting. I do not remember to have error code related to imobiliser. But i remember that years ago when thr key was not working it was orange icon on the dashboard related to imobiliser issue. I do not have even engine chek light here.

[RichardW]

Look in live data and see if cam / crank synchronisation changes to yes when cranked. It needs to see this, plus fuel pressure above 200 bar and engine rotating before it will fire the injectors.

[PaulC5]

A quick check to see if the immobiliser is recognising the key is to put it in the ignition switch and open the driver's door, most cars give a warning but if not then the key might not be being recognised.

[mostcho]

A quick check to see if the immobiliser is recognising the key is to put it in the ignition switch and open the driver's door, most cars give a warning but if not then the key might not be being recognised.

Just checked that and there was no indication on the dashboard. I cheked on my Hyundai and when i leave the key in the ignition switch and open driver door, immediately start an alarm to indicate the forgoten key. On the citroen there was nothing. Tried to crank it, left the key, opened driver door and nothing. But why then there were 288rpm engine speed and 271bars on the fuel presure live data if the keys are not recognized?

[Sloppysod]

But why then there were 288rpm engine speed and 271bars on the fuel presure live data if the keys are not recognized?

Because that's how fast the engine is being turned over by the starter. As you have fuel pressure then the pump is running

Filled up the system with fuel again with the button and nothing again. Changed BSM, nothing again. Checked engine RPM when crancing - 280. Checked pump preasure ~300 bars. No fiel on the injectors. There was 12v on the pump and there was nothing on the presure valve

So the pump is running, you have presure, an no fuel at the injectors, do you have a blockage between pump and injectors, or are the injectors not getting a signal to open, or are they blocked. Fuel as it gets old goes sticky and as you said in the first post, has your fuel clogged the injectors!
Never needed to look this deep but, on live data can you see information about the injectors?
Have you tried running it on easystart, just to make sure the mechanicals are right?
https://www.eurocarparts.com/p/holts-br ... -549771931

[PaulC5]

A quick check to see if the immobiliser is recognising the key is to put it in the ignition switch and open the driver's door, most cars give a warning but if not then the key might not be being recognised.

Just checked that and there was no indication on the dashboard. I cheked on my Hyundai and when i leave the key in the ignition switch and open driver door, immediately start an alarm to indicate the forgoten key. On the citroen there was nothing. Tried to crank it, left the key, opened driver door and nothing. But why then there were 288rpm engine speed and 271bars on the fuel presure live data if the keys are not recognized?

A look in a 2014 C4 handbook says a message should be given with the key in the ignition and the door is opened so I suspect the immobiliser is not recognising the keys. If you do not have the handbook it can be found through this topic viewtopic.php?t=63208

This is on page 131

Key left in the "Ignition on"
position
On opening the driver's door, an
alert message is displayed, accompanied by an audible signal,
to remind you that the key is still
in the ignition switch at position 1 (Stop).
If the key has been left in the ignition switch at position 2 (Ignition
on), the ignition will be switched
off automatically after one hour.
To switch the ignition back on, turn
the key to position 1 (Stop), then
back to position 2 (Ignition on).

[mostcho]

I think it is not the imobiliser and i do not know what is it.

[RichardW]

Last one says measured fuel pressure 0 - that's why it won't start. Either the fuel pressure really is 0, or the rail pressure sensor or wiring has failed.

[wheeler]

A quick check to see if the immobiliser is recognising the key is to put it in the ignition switch and open the driver's door, most cars give a warning but if not then the key might not be being recognised.

The only problem with this check I previously experimented on a Xantia or Xsara years ago & all this done was detect that there was a key in the ignition, not necessarily one matched to the car, a key from another vehicle had the same effect if it was held & removed from the transponder aerial.

I cheked on my Hyundai and when i leave the key in the ignition switch and open driver door, immediately start an alarm to indicate the forgoten key.

Hyundai's are a bit different & have a physical switch inside the ignition barrel that detects if the key is in it.

[Paul-R]

The only problem with this check I previously experimented on a Xantia or Xsara years ago & all this done was detect that there was a key in the ignition, not necessarily one matched to the car, a key from another vehicle had the same effect if it was held & removed from the transponder aerial.

But surely the fact that you couldn't turn the key in the lock would then immediately rule it out as a possibility?

[PaulC5]

Looking at the fault screens, on the third one down on the immobiliser it says Failure on recognising the key, as well as the key being in position. I am not an expert on diagnostics but does this mean the immobiliser is preventing the car from starting, as well as the lack of fuel pressure ?

[wheeler]

[But surely the fact that you couldn't turn the key in the lock would then immediately rule it out as a possibility?

Its a key left in warning so the key only needs to be in the ignition, not switched on. If you turn the car off but leave the key in the ignition & open a door it will beep to tell you, if you pull the key out it will stop, re insert it will beep again, if you switch the key for one from another car and insert it sets the beep off again. It just need to see a transponder .Form memory there is a time limit to this after the ignition is switched off & it will only do this for a certain amount of time

[wheeler]

Looking at the fault screens, on the third one down on the immobiliser it says Failure on recognising the key, as well as the key being in position.

Yeah there is some conflicting info on the live data however i would expect to see the ECU locked if the correct key was not detected.