[sean5302]

I have a 2010 316d which drops fuel rail pressure to zero as soon as the engine stops. It should be holding about 60psi ready for starting again.

I have changed the low pressure pump control module EKP
Checked the injectors leak-off. High but all the same (car has done 137,000 miles).
Checked in-tank fuel pump delivery. OK.
Checked for leaks from the rail. All OK.

So, I'm looking at the rail pressure sensor and pressure regulating valve.
The valve may not be fully closing and allowing rail pressure to go back to the tank.
I'm concerned that the sealed rail unit comprises the injectors, the valve and the pipework. A leak anywhere on these would give the trouble, which is 5 seconds cranking to start and occasional limp-mode and stalling.
Any help you can offer will be most useful, thanks.