Does it matter which overflow return line nipple is used to move to next injector?
 

Hypothetical question-

I've replaced the injector return lines on my Mercedes and 6.5 burb in the past. I've been thinking about the return flow.

How does the fuel "flow" from one injector to the next via the return line. Does it matter if you have the line on one side or the other (of the injector)? Meaning, could I put the plugged line on the rear injector on the front side nipple and the line going to the next injector on the rear side?

In thinking about it, I can't see a reason why it would matter, but I guess I don't really understand how the fuel flows. To me it seems like fuel is brought to the injector through the injector lines and any unused fuel is pushed out into the return lines on both sides (following the path of least resistance which since the back is capped is towards the front). Is this correct?

I don't think it matters which one you use.

As above it does not matter.

No it doesn't matter. It will flow off the rear most injector if you hook it up that way.

So then my explanation of the excess fuel brought to the injector following the path of least resistance to return is correct?

Yes it is.:D

The above explaination is to technical for me. You, leave only 1 way out and that is the only way it can go.

The Fuel that returns from the Injector is Fuel that leaks past the Injector Pintel and there by lubrictes it.
Unlike the Fuel Injection Pump Fuel Supply excess Fuel is not delivered to the Injectors.

And MY explanation was too technical?? :D Pintel, lubricates, fuel injection pump.... All I stated was "the path of least resistance." :P

The notion of "unused" fuel is not quite accurate. The design of the injector is such that some fuel from each cycle is allowed to leak past the nozzle valve to provide lubrication. The fuel initially supplied to the injector is routed via passages in the injector wall and sides of the nozzle and does not share a path common with the return fuel. The "return" flow is not simply excess fuel that is "left over" from an injection event. It is necessary and intended leakage past the pintle.