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If the van is experiencing low rail pressure, it is most likely caused by an injector with excessive leak off, this means that the injector is noy holding pressure, and returning the fuel back through the leak off system, and this lowers the rail pressure.
You need to start by getting a leak back test done on the injectors, this measures the ammount that each individual injector is leaking back, and indicates a faulty injector, and that injector must be replaced.
Most garages can do this for you, the equipment to do it yourself is quite expensive, and not really cost effective.
Hope this helps, if you need more help, let me know.
Well i had the injectors removed and tested at a specialist and they were found to be faulty, they were all replaced and the codes imputted into the cars computer, after a run the same fault is apparant.
Fault codes this time are P0251 and P1211.
The garage has had the van back and fitted a replacement fuel pressure regulator on the diesel pump and also replaced the diesel fuel filter but still the van has this fault, the van is perfectly driveable but when put under load in any gear other than 1st and 2nd the light comes on and its then game over until you turn the ignition off and back on again, i am now £1000 in and still have the same fault it seems.
Please help. Carl
The 2 codes together could be indicating a fault with either the ECM, or the wiring to it, as 251 rfers to - injection pump metering colntrol A, circuit malfunction (either wiring, injection pump or ECM), and code 1211 refers to - injector control pressure high or low (wiring, injector or ECM).
The 2 items in common are the ECM, which is where I would start looking, it may be that when the injectors were reprogrammed, it has confused the ECM, and it may need to be reprogrammed, this is quite common, and easily done, otherwise, check the wiring, and test the ECM with the diagnostics computer by performing live tests.