Also to add, firstly I would fit new glow plugs, they're cheap and probably dead. Paint mark the pump and pop the inlet off then undo the 2 12s and the 13 by the oil filter not all the way, give it a gentle tilt towards the block and you should...
Just done this on mine where it was fine starting with new glow plugs then had a hard start, had a recent fuel pump, pump tilt was all the way advance and reading was at 12 when fitted, it went upto 16/18 and had cutting out issues, not advised...