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.
Leak-off pipes
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.