Why 2 fuel pressure regulators?

[Clint32]

Belly-Up is that out of a silver top rb20 as im sure very other one i have seen has one at each end, but that obviously does not.

[51jay]

seems to me it is set up to negate the leaning off of cyl 5 and 6 at high boost pressures. Being a stock item it's not up to copeing with aftermarket big turbos etc.

Hmmmm! does this mean that a properly set up aftermarket regulator should actually replace the one at the rear of the rail, not just tack on in line after the front one.???

[Belly_up]

Yeah, thats off a Silver top RB20DET, out of an R32 GTS-4.

[Cubes]

So the firewall regulator lets fuel in to the fuel rail and the front fuel regulator holds fuel back to create the fuel pressure so to speak.

I don't understand why you would need to regulate the fuel coming in to the fuel rail. I would have thought only regulating the fuel leaving the fuel rail would be sufficient.

[Belly_up]

yeah i agree, unless it's a fail safe, so that in the event of the fuel reg at the exit of the rail failing to release enough pressure, the one on the entry will stop excessive fuel rail pressure, which may otherwise be able to overcome the o-ring seals on the injectors.

[R32-GTS]

Ok this should clear things up a bit. Seires 1 r32's have one fuel reg on the fuel rail . Series II r32's have an extra one on the other side of the fuel rail.

I been trying to work out why this is so . All i can come up with is that it allows more precise regulation of the fuel pressure.

And every r32 i have seen come into work all have a broken vacuum hose going to the second reg. Its a common thing. The hose just gets brittle with age.

Also the second reg doesnt work on vacuum like the primary one. only seems to read positive pressure.

[R32-GTS]

As for the clear injectors i havn't seen the, b4 .

Mine used to be red , now there yellow