vivaro 2006 cut out then wont start?

No rail pressure means no fuel so it's either the in tank pump,common,the high pressure pump or a leaking injector.
Pull the fuel line that goes from the filter to the pump and run it to a jug,now turn the ign on,don't start and the fuel pump relay will run the pump for 3 seconds.
Your looking for min of 250 ml of fuel in the jug.
Guessing you will have little or none.
Bad news is the tank has to come out to replace the pump.

1/4drive
May 2012