Fuel sending unit / digital dash

["Walter" <Whalt@xxxx>]

Matthew,

The fuel sending unit isn't that easy. It's not a rheostat like what is
used on many other cars. Instead it is a free floating thing that somehow
works by solid state. I've never taken one apart to find out. I've
installed a Tankzilla on my D, so I have the original unit that came out --
although it doesn't work -- that's why I replaced it. You might try asking
Rob Grady (of the PJ Grady outfit) to ask him to help you since he is on
close terms with whoever it is who designs the Zilla products.

As for the oil pressure gauge... I have that all figured out. It is
basically an ohmmeter. 80 psi = 80 ohms, and 0 psi = 0 ohms. There is a
non-linearity in the scale, though. You can see this from the 40 and 60 psi
readings not being at the 50% and 75% scale. I took elaborate measurements
and have data from my experiment. I am planning on publishing graphs and
what-not some time in the future, but I've got a lot of other projects that
are keeping me busy. I think I could come up with a formula that would
translate oil pressure sending unit values to dash gauge values. BUT... the
difference in the non-linearity is small. I've seen other cars that use the
same pressure gauge as the Delorean, and they didn't go to the trouble to
try to correct for the non-linearity of the sending unit. Linear or not,
the dash gauge is reasonably accurate since it is meant to be only a general
indication.

In a previous message, you gave ohm values for possible fuel level sending
units, but you were vague in the application. Are all those values things
that were used in the Delorean, or is this what Dakota Digital has to work
with? I could possibly help you with the fuel gauge as well. But since
whoever designed the Tankzilla has already figured this all out, perhaps you
could get him to talk (good luck doing this, though.)

I think the most important thing on a digital dash is to resolve the angle
drive problem. I bet if a digital dash could eliminate the angle drive,
then you could make a lot more sales. (And if this digital dash does not
eliminate the angle drive, then count me out.) Mount a pulse counter where
the angle drive mounts at the front wheel. If you can't get them to figure
out how to do it, then have them send me a pulse counter and I will make a
prototype myself if necessary! Tell them that whatever pulse counter they
send me needs to have a mechanical input that is equal to the rotational
speed of the wheel. One pulse per wheel rotation is not enough resolution
to get an accurate reading at low speeds.

To make a long story very short.... Tell them that the pulse counter needs
to be mounted where the angle drive goes, or forget it! The angle drive is
fed by a standard speedometer cable that couples to the wheel via a plastic
hub. Connecting a pulse counter here is VERY easy to do. The only problem
I could foresee is that they may need a gear drive to increase the rpm's of
the mechanical input to produce more than one pulse per wheel rotation. If
they can overcome this problem electrically instead of mechanically, then
the problem is solved and the angle drive could be eliminated.

Let me know if I can be of any further help.

Walt Tampa, FL