Re: [DML] Fuel gauge sender

["Walter" <Whalt@xxxx>]

Okay Matthew,

I got curious and took my old fuel sending unit apart. Marty was right
about it being a rheostat inside. Man what a piece of JUNK! No wonder why
the thing didn't work. Anyway, for empty the thing gives 0 ohms and on
absolute topped-off full it gives 110 ohms. Since 0 to 90 ohms is a range
that you said Dakota Digital works with, it sounds reasonable that 90 ohms
would bring the fuel gauge up to the full level (four fourths in
Delorean-iese) and 110 ohms would probably give a maxed-out gauge reading.

But PLEASE do not rely on my measurements alone. This thing is a serious
piece of junk. See if you can get some other people to agree with my
readings before you spend major bucks on having these units built.

To get these measurements, I took a defective OEM sending unit apart, and
connected a quality DMM (a Fluke model 27) across the rheostat track. Empty
obviously is a short circuit, so that gives a zero reading. Full (the
maximum value possible from the unit which uses the whole length of
resistive wire) gives a reading of 110 ohms. Due to shoddy construction,
gasoline residue build-up and weak connections, it was a bitch to get a
reliable reading. Hence, before you trust my measurements, get other
opinions.

As for compatibility with the Tankzilla: If they build the Dakota Digital
unit to have the same electrical characteristics as the Delorean gauge, then
they should be safe. My experience with the Tankzilla in my car is that it
does precisely what the directions say it wouldn't do: The low fuel light
flashes wildly after it gets around 1/8th of a tank. It continues to blink
off and on depending on whether I am going up or down an over-pass or during
heavy acceleration (as if that were really possible in a Delorean :) I
suggest asking Dakota Digital to put some sort of a delay/latching circuit
on the low fuel light so that it won't come on unless the sending unit (or
Tankzilla) says the fuel is low for perhaps 15 seconds before the warning
light LATCHES on. Then require the signal to be off for a full minute (or
better yet have the actual gas level increase significantly) before it
latches back off again. I'm quite tired of watching that useless light
needlessly switch on and off for the next 40 or so miles before it finally
decides to stay on. In fact, I suggest having the warning light controlled
by the rheostat signal alone and ignore the low fuel switch in the sending
unit regardless whether it is stock Delorean or Tankzilla.

As for the speedometer, try to find out if Dakota Digital can work with a
speedometer cable that likes to flop at low speeds. How many cars have we
all driven that has a speedometer cable that likes to whip around making the
reading oscillate over a 5 MPH range? See if Dakota Digital can handle such
a fluctuating input without giving a jumping random digital reading. It
would be nice to have a digital speedometer NOT behave like a digital ohm
meter trying to check an intermittent connection. If their speedometer
could display an average reading over, say, a 3 second interval, then such
problem could be neutralized.

I look forward to seeing the project finished. It sounds like it could be
an awesome setup.

Walt Tampa, FL

-----Original Message-----
From: Matthew P. Olans <mpolans@xxxx>
To: dmcnews@xxxxxxxxxxx <dmcnews@xxxxxxxxxxx>
Date: Monday, September 25, 2000 3:32 PM
Subject: [DML] Fuel gauge sender


>Folks,
> To anyone with a voltmeter or ohm-meter: Can someone take a reading
>of the fuel gauge in ohms when full and when empty? This is the last
>stumbling block I have with the digital dash and after this we're ready to
>order. If there's someone out there who'd be willing to take these
>measurements for me I would really appreciate it.
>
>Thanks in advance,
>Matthew
>VIN #10365
>
>
>
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