That's what it suggests to me, but how do I test it without blowing my NOS
sender? I think I will just let it work backwards.
Larry Miller
http://www.ado13.com
"If you want a Sprite, start out by asking your wife for a Porsche."
----- Original Message -----
From: Ulix Goettsch <ulix@u.washington.edu>
To: Larry Miller <millerls@ado13.com>
Cc: spridgets list <spridgets@autox.team.net>
Sent: Tuesday, June 29, 1999 9:00 AM
Subject: Re: Fuel gauge polarity?....Old Dog, New Tricks
> Larry,
> wouldn't that suggest that your new gauge is an "ammeter type" as Bob
> mentions?
> Ulix
>
> On Tue, 29 Jun 1999, Larry Miller wrote:
>
> > This is all well and good, but, based on all of this, can someone
explain
> > why my gas gauge works backwards? I just assumed it was hooked up
backwards
> > and have not bothered to swap the wires. Now I'm afraid to swap them.
> >
> > The gauge is a new Smith's gauge and the connections are not marked "T"
and
> > "B". They have no markings at all.
> >
> > Larry Miller
> > http://www.ado13.com
> > "If you want a Sprite, start out by asking your wife for a Porsche."
> >
> >
> >
> >
> >
> >
> > ----- Original Message -----
> > From: Wiedemeyer <boxweed@thebest.net>
> > To: Pete <pete@the-mix.com>
> > Cc: spridgets list <spridgets@autox.team.net>
> > Sent: Tuesday, June 29, 1999 7:31 AM
> > Subject: Re: Fuel gauge polarity?....Old Dog, New Tricks
> >
> >
> > > Frank and Pete,
> > >
> > > After reading about your experience with frying the sender unit after
> > > reversing the wires on the fuel gauge, I just had to find out why this
> > > happens. I had mistakenly believed that the fuel gauge was a simple
> > ammeter
> > > parallel type arrangement where the needle draws a very tiny amount of
> > > current for deflection while the bulk of the current is shunted
through
> > from
> > > one pole (B) to the other pole (T). If this were the case, reversing
the
> > > wires would cause the needle to deflect in the opposite direction, but
> > would
> > > not result in more current going through to the tank. After looking
up
> > how
> > > a fuel gauge actually works, (in Automotive Encyclopedia by Toboldt,
> > > Johnson, and Gauthier -- $48.50 and worth every penny) I now see why
> > > reversing the wires will burn out the sender unit: The fuel gauge is
a
> > > "thermostatic gauge", which has a very large resistance in series
between
> > > the B and T poles. This reduces the current that ultimately gets to
the
> > > sending unit. If the wires are reversed, the large resistance is
bypassed
> > > and much more current goes directly from the battery to the sending
unit,
> > > which fries it. The idea behind the thermostatic gauge seems
ingenious
> > to
> > > me because it uses the heat accummulated in the resistor to warm up
the
> > > bi-metal fuel gauge needle, which causes it to move when the ignition
is
> > > turned on. There's never any current "felt" by the needle, which
would
> > > explain why the fuel gauge itself almost never fails. I guess it's
never
> > > too late to learn something new.
> > >
> > > Thanks,
> > > Bob
> > > -----Original Message-----
> > > From: Pete <pete@the-mix.com>
> > > To: Frank Clarici <spritenut@Exit109.com>; Wiedemeyer
> > <boxweed@thebest.net>
> > > Cc: Doug Ingram <dougi@home.com>; spridgets list
> > <spridgets@autox.team.net>
> > > Date: Tuesday, June 29, 1999 9:56 AM
> > > Subject: Re: Fuel gauge polarity?
> > >
> > >
> > > >
> > > >>> Yeah. Just reverse the wires when attaching them to the gauge.
> > > >>>
> > > >>
> > > >>Doug
> > > >>
> > > >>Yes it will work but DO NOT REVERSE THE WIRES!!!!
> > > >
> > > >>If you flip the wires on the gauge you send 12 volts to the sender
which
> > > >>is grounded + connected to - = smoke!
> > > >
> > > >I can vouch for that.
> > > >Reversing the wires would be like putting the battery in backwards
(yes,
> > > >I did that)
> > > >and frying your negative earth tach instantly (yes I did that)
> > > >
> > > >I am learning a ton though.
> > > >
> > > >Pete
> > >
> > >
> >
>
> Ulix __/__,__ ___/__|__
> ..............................................(_o____o_)....<_O_____O_/...
> http://students.washington.edu/~ulix/ '67 Sprite '74 X1/9
>
>
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