[Diy_efi] Sending unit confusion

Toyota Supra turbosupramk3 at hotmail.com
Fri Feb 21 06:03:04 GMT 2003


hey mark,

sorry about the typo :) it should have been yellow, it was late

as for the signal wire, i don't plan to have it feeding into the body ecu 
and then the dash, i would like to use it to soley turn the transfer pump on 
and off. i would like the pump to run all of the time, but only when there 
is fuel to pump, hence why i am using the compartor type of circuit. 
anything about 3.2vDC is probably going to make for a very low level in the 
tank, and i'll just leave that fuel over there

let me know waht you think, thank you!!!

-j






From: "Mark Bowers & Family" <mbalntel at cfw.com>
>Reply-To: List for general do-it-yourself EFI talk <diy_efi at diy-efi.org>
>To: "List for general do-it-yourself EFI talk" <diy_efi at diy-efi.org>
>Subject: Re: [Diy_efi] Sending unit confusion
>Date: Thu, 20 Feb 2003 09:43:30 -0500
>
>Hi J,
>
>OK, I Have read you post on the voltages you are reading on the 'yaller'
>wire. The reason that it reads 12 v when disconneted is that you are
>measuring back into the open circuit that is normally the output of the
>guage or internal dash regulator.
>
>The key fact that you have measured is the 0 to 55k range of the pot. In 
>the
>best version of your application, the voltage feed will come from the
>circuit, not the dash. Question: Does this auxiliary half of the tank hook
>to a fuel guage? Will you leave this connected?
>
>While starting to draw this up today, I had a new qyestion: Do you really
>want this transfer pump running all the time? It will reduce the pump's
>reliability by a lot. An alternative is to have the transfer pump actuate 
>in
>a cyclic basis to pump so much fuel at a time. Whether this works or not
>depends on your use. If you are racing, espcially off-road or some racing
>where the fuel can easily slosh back to the auxiliary tank, it might better
>to run the transfer pump all the time, like you seem to be planning.
>
>Mark B.
>----- Original Message -----
From: Toyota Supra <turbosupramk3 at hotmail.com>
>To: <diy_efi at diy-efi.org>
>Sent: Thursday, February 20, 2003 3:46 PM
>Subject: Re: [Diy_efi] Sending unit confusion
>
>
> > ok, just to be clear, this sounds like you want me to do this in place 
>of
> > the sending unit, is there a way to make the sending unit work outside 
>of
> > the car, but putting 12vDC into the yellow wire, and then putting
>something
> > on the other side of the second wire (brown with black)?
> >
> > the particular reason this appeals to me, is i can then move the float 
>up
> > and down, and watch it turn the circuit on, and turn it off, as well as
> > visually see how much travel the float has to make, before overcoming 
>the
> > hysteresis.
> >
> > if not, i'll pick up a 55k pot today, the manual says that it should 
>read
>0
> > to 55k when functioning properly
> >
> > thanks perry
> >
> > -j
> >
> >
> >
> >
> >
> >
> > >From: Perry Harrington <pedward at apsoft.com>
> >
> > >Subject: Re: [Diy_efi] Sending unit confusion
> >
> > >
> > >Measure the highest resistance of the sending unit, then substitute a 
>pot
> > >of
> > >the same general value.  Just use 2 poles of the pot and leave the 3rd
>pole
> > >unconnected.
> > >
> > >--Perry
> > >
> > >On Thu, Feb 20, 2003 at 03:12:35PM -0500, Toyota Supra wrote:
> > > > that makes sense, so it measures the current loss, it is sending 
>12vDC
> > >out,
> > > > but after grounding or whatever, only receives 0 to 3.5vDC ?
> > > >
> > > > so, how can i simulate what is in the car? can i measure resistance
> > >between
> > > > the brown w/ black wire, and ground, and then use that resitor 
>between
> > >my
> > > > inverters ground and that particular wire? as well as running 12vDC
>into
> > >the
> > > > yellow wire?
> > > >
> > > > thanks for the help perry
> > > >
> > > > -j
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > >Subject: Re: [Diy_efi] Sending unit confusion
> > > >
> > > > >
> > > > >The sending unit may be connected like a temp sensor.  The sender 
>has
> > > > >a bias resistor between ground and the input.  12v is supplied to 
>the
> > > > >input of the sender and the output pulls the voltage up or down
>through
> > > > >the bias resistor.  If the sending unit isn't grounded, then with 2
> > > > >wires it has to be biased externally.
> > > > >
> > > > >--Perry
> > > > >
> > > >
> > > >
> > > >
> > > >
> > > > > > >
> > > > > > > > in my never ending quest to conquer this circuit, i have
> > >encountered
> > > > > > > > something very strange. when i removed the fuel level 
>sending
> > >unit
> > > > >to
> > > > > > >try
> > > > > > > > and test my circuit, i found that i am not able to simulate
>its
> > > > > > >electrical
> > > > > > > > function.
> > > > > > > > the sending unit has 2 wires, a yellow and a brown w/ black
> > >tracer.
> > > > >when
> > > > > > >the
> > > > > > > > sending unit is not plugged into the body harness, the 
>yellow
> > >wire
> > > > >has
> > > > > > > > +12vDC (or whatever battery voltage may be) on the body
>harness
> > >side
> > > > >of
> > > > > > >the
> > > > > > > > connector, and the brown w/ black tracer has approximately 
>15k
> > >of
> > > > > > >resistance
> > > > > > > > to ground, or 35mV of positive voltage.
> > > > > > > >
> > > > > > > > when the connectors are plugged in, the yellow wire will 
>have
> > > > >anywhere
> > > > > > >from
> > > > > > > > 0 to 3.5vDC, dependent on the position of the "float". the
> > >variable
> > > > > > >resistor
> > > > > > > > will have resistance ranging from 0k to 55k.
> > > > > > > >
> > > > > > > > now, my problem is, i can't simulate the variable voltage
> > >outside of
> > > > >the
> > > > > > > > vehicle, to test my circuit. if i put 12vDC into the yellow
> > >wire,
> > > > >the
> > > > > > >brown
> > > > > > > > w/ black tracer will also have 12vDC, so what could that 
>wire
> > > > >possibly
> > > > > > >be
> > > > > > > > doing, or connected to, that would make the circuit and unit
> > >work
> > > > > > >properly?
> > > > > > > >
> > > > > > >
> >
> >
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