Delphi-Common Rail System – High-pressure fuel lines and leak-off pipes
High-pressure fuel supply lines
NOTE: The bending radii are exactly matched to the system and must not be changed.
NOTE: After undoing one or more high-pressure fuel line(s), it/they must be replaced. Reason: The reason for this is that leaks can occur when re-tightening, due to distortion of the connections of the old lines.
The high pressure fuel lines connect the high-pressure pump to the fuel rail and the fuel rail to the individual fuel injectors.
Due to the operating principle of the fuel injectors work (see section “Fuel injectors”), some of the fuel is drained from the fuel injectors as leak-off fuel and led into the fuel return system.
A faulty fuel injector (leaking at the solenoid valve) can be detected by measuring the quantity of leak-off fuel from all the fuel injectors over a specific period of time, using special collectors (special tool).
If the quantity of leak-off fuel differs for one (or more) fuel injector(s) (see current Service Literature), this indicates a leak in the fuel injector.