I noticed a puddle of diesel around the 2 middle fuel injectors, so I took it into a local garage and he told me that it's most likely the leak off pipe that need replacing.
It's normally obvious if it's the leak off pipes. How was the little O ring on the leak off tapping on the injector?
So I've brought it and put it on and the leak is still there but I cant see where it's coming from.
The leak off on the FL2 is a high pressure leak back system, which runs at 10 Bar or 145 PSI. This high pressure is needed for the injectors to function, as there is no mechanical connection inside, just a column of high pressure fuel from the leak back system. Sometimes the leak back pressure control valve (silver part in the leak back pipe) can fail, causing over pressure or under pressure, but it's not common, and would seldom leak from just 2 injectors.
Anyway my question is that my Haynes manual says that if I put in a new fuel injector I need to have the serial number so I can program it to the ECU? Is this correct? as I dont mind changing it but wont be able to if the ECU needs programming.
The injectors need to be coded to the EDC, or more accurately the EDC needs to be programmed with the injector codes, so it knows the injector's characteristics.
This is important for proper injector function, fuel economy and emissions reasons.
However the chance of the injectors causing the leak is tiny. Looking at the picture, it looks like the injector is black with sludge, which is a classic symptom of copper washer seal failure. The copper washers seal the bottom of the injector to the head, and only a tiny leak will allow fuel from the injector to be forced out of the seal under compression, causing the issue you have.