[Diy_efi] Return line and oxidation was: Fuel Regulators

[Marteney, Steve]

On the subject of systems with return-lines, there is a very small
disclaimer in the back of the Aeroquip catalog that cautions the use of
their hoses in an EFI system with a return line.  They stated the gas can
oxidize in such a system and then attack the inner liner of the hose (or
something to that effect.)  Anyone know the scoop on this or have
encountered any problems?  I'm wondering if that warning would just apply to
the use of their hoses for plumbing the ENTIRE system tank-to-rails vs. just
using short hoses to plumb in a regulator and such.

Steve

-----Original Message-----
From: bill.shurvinton at nokia.com [mailto:bill.shurvinton at nokia.com]
Sent: Tuesday, August 20, 2002 3:45 AM
To: diy_efi at diy-efi.org
Subject: RE: [Diy_efi] Fuel Regulators


I think there are 2 issues here

1. Vac referencing the regulator
2. Return lines

1. Depends upon a number of issues. The vac reference just ensures that the
pressure differential between fuel rail and manifold is constant. If you are
getting the engine mapped on a dyno and have enough injector dynamic range,
you don't need it. If you are running big injectors it 'can' help get idle
PW managable. 

2. I haven't seen a high pressure (35+PSI) EFI system that uses a regulator
before the fuel rail, but what do I know. There are ways of doing a
returnless system but they are considered 'tricky'. For racing the old
fashioned regulator after the rail is known and works. KIS

The main reason for a return line is to ensure 'fresh' fuel and to prevent
the possibility of vapour lock and other nasties. 

Bill
-----Original Message-----
From: ext Mark [mailto:mark at szutta.com]
Sent: 20 August 2002 01:25
To: diy_efi at diy-efi.org
Subject: [Diy_efi] Fuel Regulators


Hi Folks,

Just building the fuel rail for my project and I'm a bit confused about the
regulators.  I have a external pump with a regulator just after the pump.
Are there any real issues with just uning this regulator and not having a
return line ?  Many setups I have seen have a secondary vacuum controlled
regulator running to the return line.  As I'm unsing this setup in a race
car with a fairly agressive cam I would have thought that the vacuum
regulator would cause more problems than helping?

Thanks,

Mark S.

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