feed and return...

[sen2two]

just wondering...

so i normally feed my primary rail first. but with both rails having the regulator on the end, (stock FC rails) would it even matter if you were to feed the primarys or secondary rail first?

[sen2two]

no one here ever ran the feed to the secondary rail first?

i know i have before, but not with the stock rails. im just curious if it would cause a problem on a pretty stock car with stock rails.

[Mobius]

From what I remember a FC doesn't have 2 regulators. One is a Fuel Pressure Regulator, and the other is the fuel pulsation dampener. It does matter which rail you feed first, because the Fuel Pressure Regulator has to be the last thing before the fuel return line.

[NoDOHC]

Actually, this depends on whether the FC is Turbo or NA. The turbo cars feed the secondary and return out of the primary, while the NA cars feed the primary and return out of the secondary.

Basically, if it has a vacuum line port, it is the FPR. If it not, it is a pulsation damper.

[sen2two]

so a rule of thumb could be, feed to where the pulsation dampner is. wich has the vacuum line coming from it...

wich in my case, its turbo. so feeding to the secondary is the way to go...

[RETed]

FPR is ALWAYS the last thing the fuel flow sees before it goes back into the gas tank.

All US-spec FC turbos should have the FPR on the secondary fuel rail.
Thus, fuel feed line should hit primary fuel rail first then secondary.

I've seen J-spec FC (they are all turbos) have the FPR's on the primary fuel rail, and their fuel system is basically backwards from the US-spec cars - secondary first and then primary.

If you indeed have FPR's on both primary and secondary fuel rails, you might have a mix and match of US-spec and J-spec fuel rails.


-Ted

[NoDOHC]

huh... I guess the two I have had were both JDM swaps (although I was told that they were original).

Interresting....

Either way, what RETed said is the simple way to remember it, return line leaves the FPR.