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Why 2 fuel pressure regulators?

Cubes

By Cubes,
in Engines & Forced Induction

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51jay Mentor

51jay

Posted
Posted

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.???

Cubes Grand Master

Cubes

Posted
  • Author
Posted

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 Contributor

Belly_up

Posted
Posted

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 Mentor

R32-GTS

Posted
Posted

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.

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