micheldeman wrote:I have read somewhere that the hpp (high pressure pump) should build up a pressure to the rail/injectors around 200 bar during cranking, 300 bars at idle and anything from 1200 to 1800 bars running.
The delphi units have a higher pressure than the other HDi injectors, but 1800 sounds about the right ballpark figure.
micheldeman wrote:Also the pressure goes rapidly from 120 back to 30-40 after the engine stops.
So, there must be a major leak.
The system will quickly depressurise the common rail by opening the leakoff function of the pump sending the excess fuel back to the tank.
micheldeman wrote:Probably the biggest result of injector failure is due to the injectors having excessive return flow or back leakage. This is due to worn parts which allow excessive fuel to go through the diesel injector and to return back to the tank or fuel system. This causes a drop in rail pressure (see "low fuel pressure") which results in hard starting or not starting at all.
The easiest and least intrusive way to test for excessive leakoff is to do a leak off test, you can test all 4 injectors at the same time.
This is the leak off topic (here)
micheldeman wrote:I must admit that I have removed the top part from the injector before I removed it completely from the head. So will take out that injector again and see if I can get it under pressure and test. I also had to use a spanner to lift and hammer it out from the head.
They can be difficult to get out
It may be damaged and would explain a few things.
micheldeman wrote:I have read about bump starting, but that involves risks for the timing belt?
The timing belt is at no more risk from a bump than a jump or normal start. The reasons timing belts break is because they don't get changed when they should. Bump starting is for starting the engine when the starter motor can't turn the engine over due to a flat battery or failed starter/solenoid. If you starter motor system can turn the engine at a reasonable speed, I can't see any bump starting helping you.
micheldeman wrote:Or there may still be air in the pump itself that doesn't want to come out.
If you didn't remove the common rail, I don't think you would get air into the pump, but its building up pressure so I don't see its a pump issue.
Is yours the 8 valve or 16 valve C3?