[Diy_efi] Donegan ECU

[Mike]

At 08:33 AM 1/5/07, you 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

On my vehicle there is a "swirl pot" on the exit of the fuel return inside
the bottom of the tank, this produces a nice vortex around the low
pressure fuel pump so its strainer is constantly agitated and therefore
cleaned of any debris, quite a nice and elegant aside :)

In any case, to avoid the embarrassment of explaining those odd gurgling
noises to the nice cute female passengers, I would suggest not having a
top return but the swirl return as low as possible, far less chance
of gurgling burping type noises at inconvenient moments ;)

Rgds

Mike
ps: Dont go to bed on an empty stomach, take her to dinner first...




>----- 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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