[Diy_efi] Donegan ECU

[Steven P. Donegan]

I have not seen/heard any reasons on where to return fuel to in the tank
- unless otherwise informed I would assume anywhere is fine...


On Thu, 2007-01-04 at 19:33 -0500, Mike V wrote:
> Related to this, is it okay to have the return line squirtin
> the fuel in from the top of the tank, or should it be submerged
> in the fuel?  I have a 1941 gas tank that I need to plumb a return lin into.
> Cheers,
>  MV
> 
> 
> ----- Original Message ----- 
> From: "Bernd Felsche" <bernie at innovative.iinet.net.au>
> To: <diy_efi at diy-efi.org>
> Sent: Thursday, January 04, 2007 6:00 PM
> Subject: Re: [Diy_efi] Donegan ECU
> 
> 
> > On Friday 05 January 2007 00:57, Steven P. Donegan wrote:
> >> I had not thought of fuel temp at all - every vehicle I drive
> >> would consume the gas in the rails well before it got warm :-)
> >> However this does raise a point - perhaps my ECM/PCM/EFI computer
> >> needs a way to open a fuel return line and to sense fuel temp in
> >> the rails? Any ideas on how useful that would be in the 'real
> >> world' anyone?
> >
> > Superflous if you're running in closed-loop; which you would be if
> > the fuel rail was warm enough to make a difference.
> >
> > If the temperature in the fuel rail is a problem, then a
> > recirculating fuel pressure control system is IMNHSO a better
> > solution. In such a system, there's always "fresh" fuel that's in
> > excess to the amount required for injection from the tank flushing
> > the rail(s). The fuel tank is the cooling environment for the fuel.
> >
> > Pressure regulation also happens at the rail(s), whereas in
> > "dead-end" systems it's at the fuel pump, perhaps a several metres
> > from the rail and therefore the injectors. That increases the
> > difficulty in controlling the pressure (time delays that depend on
> > fuel pressure and temperature); especially if it's to vary
> > dynamically wrt manifold pressure.
> >
> > The ability to vary the fuel rail pressure is at least desirable to
> > get consistent injected quantities due to a fairly constant pressure
> > difference across the injector; between the fuel rail and the
> > manifold where it's injecting.  Makes for simpler calculations on
> > injected quantity.
> >
> > If you're stuck with a "dead-end" fuel delivery system, then you
> > need to add a return line and a valve that vents the rail(s) back to
> > the tank in the interval between the fuel pump running and the
> > engine actually being started. The time delay will depend largely on
> > the free-delivery rate of the fuel pump and the volume of the fuel
> > rail(s). That ensures that there's "cold" fuel in the rail(s) before
> > you start injecting it.
> >
> > -- 
> > /"\ Bernd Felsche - Innovative Reckoning, Perth, Western Australia
> > \ /  ASCII ribbon campaign | "If we let things terrify us,
> > X   against HTML mail     |  life will not be worth living."
> > / \  and postings          | Lucius Annaeus Seneca, c. 4BC - 65AD.
> >
> >
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