648 No start low rail pressure

[MB140300SD]

Any 648 experts here? I picked up a very nice 05 CDI at auction that had no keys. From the oil change sticker in the window it appears to have been recently serviced by a local MB only well known indy. It also has a set of brand new Michelins. Looked like it was a 1 owner car but was traded or sold to Carmax (had a Carmax stock tag in the in the window), then a small used car dealer bought it at auction. I suspected they lost the keys to it and just sent it back to auction and I half hoped it would start right up once I got a key for it. The key arrived yesterday and it cranks but no start. I threw the DAS on it and get code 2051 (001) low fuel rail pressure. I ran thru the tests for the low pressure side that is basically hook pressure gauge to supply side of filter, enter value into DAS, then hook it to output side of filter and enter the number, then hook line and run it into a container, system runs pump for few seconds and you measure the volume and enter that. Low side tests fine. The next step would be to test injector volume which involves the use of a special tool that you install on the return lines of the injectors and measure the volume. I do not have this tool so I can't do that. This is my first 648 so I thought I would ask to see if there are any common issues that could cause this error code and no start condition? I swapped out the quantity control valve on a 642 chasing phantom issues so I still have the valve off that car (I think they are the same part). I think tomorrow I may try swapping that out and see what happens. Any thoughts?