[Diy_efi] Re: CIS EFI via Fuel Pump PWM

[Kenny Bauman]

Not sure I understand the 100:1 range needed of the
pump.

Perhaps you can clarify?

The CIS injectors only see a range of 45 to 60 psi
during operation. I think some of the dynamic range is
handled by the PWM effect of the injectors themselves.
Remember they have a spring loaded valve that
constantly closes and opens. Sort of a mechanical PWM
that changes with pressure. Which of course changes
flow. But I really don't have that good of an
understanding of it all.


I think part of the original intent has been lost over
the posts. The orginal idea was a dead nuts simple
system that did away with the fuel regulator and
return line.

Ken Bauman



Message: 2
From: Bernd Felsche <bernie at innovative.iinet.net.au>
Subject: Re: [Diy_efi] CIS EFI via Fuel Pump PWM
To: diy_efi at diy-efi.org
Date: Thu, 8 Aug 2002 09:00:46 +0800 (WST)
Reply-To: diy_efi at diy-efi.org

steve ravet tapped away at the keyboard with:
> I missed something also.  Was the intent to PWM the
pump at a high
> frequency to get a variable fuel pressure, or to use
the pump to
> actually create pulses of fuel?

The former.

One thing I didn't mention before is that the pump
needs to have a
dynamic range covering all the fueling requirements of
the engine;
that's around 100:1.

Probably far simpler to use a (large) PWM fuel
"injector" on a
return line to regulate the pressure to CIS injectors.
Some sort of
pressure damper downstream, before the CIS injectors
is advisable.

-- 
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Western Australia
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