Fuel supply and return which is which?
 

This is a bit of an embarrassing question that I could have answered myself if I still had the original engine in the car but does anyone know what is the fuel supply and what is the fuel return line? I shamelessly stole this photo off another thread so if its your photo thanks. :cheers:

http://986forum.com/forums/uploads02...1475163209.jpg

Can't answer from the pic, but the fuel filter is close by. Trace from there?

I`m pretty sure the right one is the return line.

I would think but don't know that the larger line ( blue arrow ) is the supply and the smaller is the return . Hopefully someone smarter than me :D will chime in .

Man I should have made this a poll!

The one with the blue arrow should be connected to the fuel pressure regulator on the injector rail, and should be the feed line on a 97.

https://lh3.googleusercontent.com/pr...o5nLzdFq_4tTAw

The fuel pressure regulator is installed on the feed line on Porsches? How does that work? Now I'm really confused.

On the early cars, it was a vacuum operated diaphragm device on the fuel rail, as in the diagram.

https://i.ebayimg.com/images/g/R4AAA...a2l/s-l400.jpg

The early fuel system included a return fuel line and had a fuel rail mounted fuel pressure regulator. For 2002, there is no return fuel line and the fuel pressure regulator is mounted in the fuel tank.

OK, seems after checking the early service manual, I have the lines reversed: The fuel pressure regulator in on the return line. Sorry bout that......��

Right, but typically these regulators are installed after the rail to ensure they are maintaining rail pressure (unless I’m wrong). Do I have this backwards?

See my previous post; seems my memory is not as good as it once was, but the service manual's always is................

Great thanks! I really need to get one of those service manuals and stop abusing you guys. thanks for all the help.

I think the question was also wrong :) So, just to clarify, the right one that runs from the regulator is the return line. The left one (red) is a vent line. The feed line is not pictured, it is on the other side of the rail and is coming up from the fuel filter on the right side of the car. At least on mine, which is a 99 Base.

Ha! What a rollercoaster. Join us next week for: What are these “coolant” lines?

My fitting at the blue arrow is slightly wet/weeping. Does anyone know whether there is an o-ring in the disconnect fitting that can be replaced? Other options of repair? And my vote is that it (blue arrow) is the return line (98 base)

Mine was leaking too, but not at the connector, but at the fuel rail, and it was leaking down on the back side of the line. If it leaks at the connector, it`s also possible that the line itself is scratched where the fitting slides onto.