[Diy_efi] Re: Looking for circuit to turn transfer pump off at certain

Toyota Supra turbosupramk3 at hotmail.com
Thu Nov 14 20:21:51 GMT 2002


so far this seems like the best choice, i will take me a while to build the 
circuit, but since everyone has been so nice to offer suggestions and such, 
i will probably sketch something up after i am able to figure out a circuit 
(probably at least a week :( ) and then post a link for the list to 
critique. thanks thomas!

-j






From: "Thomas L. Frobase" <tfrobase at ghg.net>
>Reply-To: diy_efi at diy-efi.org
>To: <diy_efi at diy-efi.org>
>Subject: RE: [Diy_efi] Re: Looking for circuit to turn transfer pump off at 
>certain voltages
>Date: Mon, 11 Nov 2002 20:19:37 -0600
>
>Well this is how I would approach the problem, Motorola now makes a 8
>pin microcontroller that uses the same instruction set as the Megasquirt
>project http://www.bgsoflex.com/megasquirt.html it has several Analog to
>digital converters as well as status outputs, using the processor you
>will be able to monitor the analog level of the tank and turn on and off
>the pump as appropriate, it should require a handful of components and a
>relay driver for the pump.  The controller uses pretty much the same
>tool set as the megasquirt as well as having an internal oscillator as
>not to require a crystal.  Sure, I know it will take a bit to program
>the chip but in the end it will be simple reliable and inexpensive, the
>single price for the chip MC69hc908QT4 is about $4.00.
>
>... tom
>
>-----Original Message-----
From: diy_efi-admin at diy-efi.org [mailto:diy_efi-admin at diy-efi.org] On
>Behalf Of Bevan Weiss
>Sent: Sunday, November 10, 2002 11:32 PM
>To: diy_efi at diy-efi.org
>Subject: Re: [Diy_efi] Re: Looking for circuit to turn transfer pump off
>at certain voltages
>
>
>
>----- Original Message -----
From: "Toyota Supra" <turbosupramk3 at hotmail.com>
>To: <diy_efi at diy-efi.org>
>Sent: Sunday, November 10, 2002 4:02 PM
>Subject: Re: [Diy_efi] Re: Looking for circuit to turn transfer pump off
>at certain voltages
>
>
> > hey bevan, thanks for the reply, maybe this will help clarify ...
> >
> >
> > here are the specifics, my gas tank is a saddle tank, meaning that it
> > has two sides to it like saddle bags on a horse. now the pumps are on
> > the left side, and the mechanical venturi valve that used to transfer
> > the fuel from the right side, had to be removed.
> >
> > so my dilema is, how do i get fuel from the right side of the tank, to
>
> > the left side where the fuel pumps sit, so that i am not driving
> > around on
>only
> > a 1/2 tank of usable gas, even though the entire tank is full?
> >
> > well, my design thought was to have a transfer pump intank, that drew
> > from the right side, to the left side, at all times that the car was
> > on, except for when the right side of the tank got low on fuel. this
> > is because the fuel acts as a lubricant to the transfer pump, and if
> > it ran dry for any period, it would probably burn up.
> >
> > so the way i decided to control the transfer pump was to use the
> > existing sending unit that is in the right side of the tank (which
> > reads 0 to 3.5v, full being 0v - bone dry being 3.5V) and use that
> > sending units output as
>a
> > reference signal for the circuit, and having that circuit turn a relay
>
> > off (or on) to control the power to the transfer pump.
> >
> > i appologize if this reads confusing and that it is so long, but i
> > wanted
>to
> > be as detailed as possible. if you think your circuit design would
> > work,
>i'd
> > be very grateful if i could have a copy of it. thank you for the reply
>
>Hmm, so you can't just have a tube connecting the two saddle-tanks
>together at their lowest point (to distribute the fuel evenly over both
>tanks), this would certainly be the easiest way to let the pump see two
>tanks.  I realise that having the tanks connected in a more vertical
>manner would be a better solution but it may not be worth the trouble.
>
>I can't think of an optimum way of doing this (easily), as even a
>comparator type circuit isn't what you really want, it would mean that
>the pump is on when the tank is near full and off when the tank is
>getting empty, which isn't an optimum idea, you wouldn't be able to use
>all the fuel this way....
>
>I think perhaps that looking outside the usage of a pump is required...
>(or perhaps a non standard type of usage).
>
>I have no real ideas about this kind of stuff, only the electronics and
>that's not the ideal solution to this one.
>
>FWIW, the comparator circuit that I was refering to was a simple opamp
>(ie 741), with a VREF on the non-inverting input that is the switching
>point of your fuel tank, and have the inverting input connected to the
>actual fuel sensor itself (after sufficient low pass filtering).  Then
>you can add in some hysteresis if required/desired simply by applying
>some feedback to the circuit ( a resistor/voltage divider from the
>output back to the non-inverting input).
>
>_______________________________________________
>Diy_efi mailing list
>Diy_efi at diy-efi.org http://www.diy-efi.org/mailman/listinfo/diy_efi
>
>
>_______________________________________________
>Diy_efi mailing list
>Diy_efi at diy-efi.org
>http://www.diy-efi.org/mailman/listinfo/diy_efi


_________________________________________________________________
STOP MORE SPAM with the new MSN 8 and get 2 months FREE* 
http://join.msn.com/?page=features/junkmail


_______________________________________________
Diy_efi mailing list
Diy_efi at diy-efi.org
http://www.diy-efi.org/mailman/listinfo/diy_efi



More information about the Diy_efi mailing list