diesel injector leak off pipes????

[8304]

a question for sombody in the know out there....

have read many a time that leaky diesel leak off pipes can let air into the fuel system and cause lumpy running etc...

but-----

looking at the piping on the car, the leak off pipe runs into a tee piece on the back of the pump -
1 part going into the pump
1 part going into the fuel return to the tank and
1 part into the leak off pipes.

My question is surely when the car is running the return pipe from the pump is not constantly full of fuel there must be air in that line as its just a return so this would open the ends of the leak off pipes to air in that return pipe - (through the tee piece). Surley that would be exactly the same as if one of the leak off pipes were leaking??..

any thoughts??


alastair

[jeremy]

You will only get air problem from the leakoff pipes if you have a Bosch pump.

As the return system operates it will purge itself of air and will hold unused feul which is pumped along as more unused fuel enters the system. Air can only get in through leaks (which aren't there now you have new pipes) and porosity of the pipes (minimal) and the fuel column will remain solid.

take a piece of hose or pipe, immerse it COMPLETELY in water and put your finger or thumb over one end, lift the pipe out of the water and hold it vertically. Some water will remain in it as can be demonstrated by removing your thumb.

jeremy