I have a 2005 E320 CDI with has the check engine light and does not have acceleration. Took it to mechanic, and he replaced EGR valve, Fuel filter, motor mounts on engine and transmission. It still shows the low fuel rail pressure when accelerating and shuts down. Mechanic has it for 3 weeks. But gave back to me and states he has exhausted all of his troubleshooting and told me to take it to the Mercedes authorized dealership. Any ideas?

 

on the end of the rail is a regulator of some sort. They rarely go bad but if off by just a little it does not run or run right. Just my guess.

 

Does it only shut down when you load it up? If you hold the brakes on hard and floor it, wait for peak power/rpm and then let go of the throttle does it stall then? If so then you most likely have a injector that has worn out internally (excessive leak off).

To identify the injector you need "leak off tubes" http://www.ebay.co.uk/itm/Diesel-Inj...ht_3144wt_1161

You put these tubes in the top of each injector and it will show how much fuel is leaking from the injector (normal for lubrication purposes)when the engine is running. You'll most likely find one is "leaking" much much more than the rest. if they are similar at idle then load the engine up and then the faulty injector will be obvious. There is a automated test for this using SDS but it's not required.