fuel rail pressure cranking

[james hallett]

Hello all. This is my first post so be gentle.
I have a citroen relay 2.2 hdi Puma 120 22 dt
Vin VF7**************[VIN obfuscated, can be read by forum staff].
Over the last month starting performance has declined. It can now take 10 mins of cranking, letting the low pressure pump cycle a few times etc . One cylinder usually fires immediately, (enough to disengage the starter) but no others join in.
A leak off test revealed two producing much more than the others, (one nearly twice, and one a third more than the "good boys"), and they were replaced, ( as were the glow pugs just in case), but no improvement.
If I disconnect the rail pressure sensor it starts a little easier, but run unevenly. When it does start and the pressure sensor is conected it runs fine
Diagbox reports rail pressure at 280/ 300 at idle. Diag reveals no faults.
I am comming to the conclusion that my high pressure pump to too worn to produce sufficent pressure under cranking to fire the injectors up. Does anyone know what the desired rail pressure under cranking is for this engine. And is electrically unpluging the injectors and cranking while connected to diag box a feasable way to measure it.
Sorry for the longwinded post. Jim

[Paul-R]

How many miles has the vehicle done?

[james hallett]

clock says 95676

[RichardW]

Generally want to see about 200 bar on cranking.

[james hallett]

thanks Richard will give it a go tomorrow and report back

[james hallett]

Morning Richard, Hello dont know if I'm posting this twice (it didnt seem to appear in the thread the first time). On connection of diag there was no presssure. After 5 secs of cranking it was about 650. On ceasing cranking pressure fell to 250 after 5 secs, and 0 after 20 secs. No visible high pressure leaks. Is this normal, or is the pressure regulator kaput. I have ordered a cheap ebay pressure sensor as a controll. Ta
Jim Hallett

[james hallett]

On doing a bit more research I realise something is kaput!
Is there any way to find out if its a regulator or an injector without;
1)high pressure testing equipment
2) sticking on new bits one at a time to see if it helps.
Ta Jim Hallett

[civvie]

Daughter had some problems starting her Clio we changed the fuel filter and that inproved it somewhat, has the fuel filter been replaced lately or is it original.

[james hallett]

Thanks for the reply, fuel filter is new, and I'm pretty sure its a high pressure side prob.
I dont know how efficient dpfs are are, but in relation to the fuel regulator / injector leak decision, wouldn't I get smoke with an injector this leaky Jim.

[RichardW]

Are those numbers bar? 650 (bar)seems a lot on cranking, but I don't know this engine specifically. Does it report engine rpm when cranking - you should see 180-200 rpm. Does it register air flow from the MAF? Does it show cam/crank synch changing to yes as you start cranking?

[james hallett]

Hello Richard,
Once again many thanks. Yes I believe diagbox reports in bar.
The maff reading rises from 0 to 24
The crankshaft reading went from "No" to "yes".
Didn't see rpm reading.
During my last pressure reading a battery charger was connected, without charger its 550. Again it fell to 0 quite quickly. Weather this is because the injectors are unpluged, (ecu realises that its pointless sending fuel to a closed injector), I dont know. Jim

[RichardW]

If cam synch went to yes, it must be able to see the crank signal. It would appear to have everything it needs to start. Does it smoke when cranking?

[james hallett]

No no smoking. After it has started it runs well which - steers me away from leaky injectors.
So you think the fall in rail pressure is a red herring?
As I said it always fires one cylinder immediately which disengages the bendix. My theory was that as soon as the bendix stopped turning the flywheel the rail pressure would drop (due to the faulty fuel pressure regulator), and the ecu would "switch off" subsequent injectors. However a neighbour who is an experienced mechanic came and had a look and he diagnosed a faulty bendix. He thinks it should stay engaged for two or three cylinder firings -untill the motor really takes over the running of the high pressure fuel pump. Unless anyone knows better I suppose I will have to replace both. Thanks
Jim

[james hallett]

Hello all
A new starter seems to have sorted the problem.To anyone else experiencing these problems, (namely one cylinder firing- this disengaging starter, but failing to start the engine), it may be a worn bendix. I had always assumed that the starter was supposed to disengage immidiatly, but apparently not. Its probably exacerbated by a high millage engine.
Thanks for the replies. Jim Hallett