I have a W251 2006 R320 cdi and having an issue for not starting, it cranks then it will start for a 1-2 secs then it will dies but then you can always start again and again but only 1-2 second enigine runs...

I have sent the Hi-pump to get it checked plus replaced the lo-fuel pump (in the tank) i have replaced fuel filter and the Glow Plugs even the module because it was showing that it was faulty but then still the same issue...

i am guessing it has a low pressure of fuel, the reason i said that... I loosen up the high pipe coming from the hi-pump and the fuel there was dribbling, i have checked the fuel pressure between fuel tank to fuel filter and showing 55-60psi and the i checked the between fuel filter to hi-pump and showing 55-60psi also..

i ran out of ideas please help, if you have same issues and sort out the problem... thank you!

 

You have a high pressure fuel issue,stop guessing,find someone with the diagnostics\tools and experience to help as this is not a light bulb DIY issue!