Low pressure fuel

[Jayneb260189]

Hi I currently have a c220 cdi 61 reg and it's gone in to limp mode with low fuel pressure and soot is on back bumper seems to only happen when I accelerate hard
Had injectors and dpf done at merc Sheffield

 

[Uncle Benz]

Are you sure it’s low fuel pressure and not low boost pressure? A split boost hose will make lots of black smoke from the exhaust and limp mode

 

[Jayneb260189]

Definitely low fuel pressure
I was thinking it could be the fuel quantity control valve
Is this located on the hp pump

 

[LostKiwi]

Low fuel pressure will generally cause white smoke not soot.
As above that sounds like a split hose or holed intercooler.

 

[Jayneb260189]

After reading the codes it also comes up with high fuel pressure code aswell
The fan kicks in all the time aswell but seems to be nothing wrong with it or the horses

 

[LostKiwi]

What are you using to read the codes?
Also have you looked at live values while the car is running to check what the pressure is doing?

 

[Jayneb260189]

Im not sure what code reader is being used it was done by a local garage. Could it be the fuel quantity control valve or not
I have a new one to fit but cant see where it is any help would be great thanks

 

[LostKiwi]

I'm still sceptical it's the HP fuel system.
Soot is over fuelling relative to air available. Split hoses on these are very common and give the exact symptom you describe.

 

[Jayneb260189]

Ok thanks I'll double check all hoses again is there anything else to look for while checking

 

[LostKiwi]

Check intercooler for leaks too. The salt on the roads corrodes them and they rot through. Fairly easy to pressure test if you make up an adapter. Simplest way is to make up blanking plugs from wood (or anything else suitable), fit a bike valve in one then use a bike pump to pressure test to 20 psi and see if it holds.

 

[Jayneb260189]

Think I've found the problem
Its the 4th injector AGAiN
How do I find out if my injectors are coded thanks