Blinkdagger

Hi guys
I'm trying to finish my setup and have questions about routing the fuel lines. The chassis is nb1 so it's returnless system. I have radium fuel rail with pumbing kit. I have two port at the ledt side of the rail，can I use them for the fuel regulator？The fuel regulator I have is Fuel lab 515series. Any advice would help，thanks！

Siks6

I'm asking this too, has this worked for you? If so I want to know what else you did.

codrus

The regulator needs to return fuel to the tank, so no, this won't work.

You have two choices -- you can either convert to a return fuel system by running a new line from the tank up to the engine bay (don't use the evap line, that is too small IMHO), or you can set up the regulator like the FM "big fuel kit" for NBs works.

--Ian

rwyatt365

Once you go full return you won't go back! I balked at this for years on my NB1 because I thought it was "too complicated" and I might screw something up and die in a flaming fireball. I did it a few weeks ago and I haven't died yet!

deezums

iTrader: (3)

A FPR like this is a regulated leak, anytime fuel pressure is over the set pressure the leak will leak more to keep the rail pressure at the set point.

What you have depicted won't work because the rail pressure is going to be higher than the leak pressure, no fuel will ever move through the regulator and even if it did it would serve no purpose as all the excess flow is directed right back into the rail.

You've gotta let the return out to atmospheric pressure. Anything else is a no-go.

codrus

I found the diagrams I threw together a while ago to explain the routings:

Stock is stock, fairly self-explanatory. All of the lines are regulated, but the regulator is not manifold-referenced so your effective fuel pressure drops as boost climbs.



The FM BFK-style routing is to replace the factory filter near the rear wheel with an aftermarket regulator and filter. It regulates the pressure on the line that goes up to the engine bay and dumps the excess pressure back to the tank. Downside to this is that their kit involves deleting the pulse damper off the fender which means there's "noise" in the fuel pressure as the injectors open/close. In principle you could keep that damper, but it's a restriction compared to the -6 AN lines that their kit uses, so I replaced it with a damper from Radium. Probably overkill.

The regulator has a reference port on it, so you can get manifold-referenced pressure if you run a vacuum line back to the rear wheel (I did, works well).



Return system requires adding a second line going between the tank and the engine bay, which is kind of a PITA to snake past the transmission.



--Ian