[rescue] LCD monitor diagnosis

[Phil Stracchino]

Geoffrey S. Mendelson wrote:
> On Thu, Apr 27, 2006 at 03:12:51PM -0400, Mike F wrote:
>>I wonder if something like this is even feasible; the big problem to
>>overcome in a weight-based system is g-force. 
> 
> It's really a case of it works, don't fix it.

No, it DOESN'T work.  That's exactly the problem.  Or, it works, but
just barely.  I've driven cars where the guage could sit on empty for 40
miles and you still had 4 gallons of gas in the tank.  I've driven
others that ran out of gas with the guage still showing an eighth of a
tank.  I've driven cars with fuel guages that sat at or close to full
while you drove two hundred miles, sank slowly to about half full in the
next hundred, and then dropped precipitously over the next 50 miles.
The system we use now is about 80 years old, it's a piece of outdated,
inaccurate, unreliable crap, and the only reasons people put up with it
are because they don't have a better option and because it's always been
that way.

You can't rely on a standard fuel guage.  It gives you a rough
indication of more or less how much fuel you have to the nearest
quarter-tank or so.  In practical terms it means you need to think in
terms of refuelling any time the guage gets near a quarter tank -- on
some cars, a half tank.

Sure, we got by with it for 80 years.  We also got by with carburetors,
bias-ply tires, unassisted drum brakes, non-safety-glass windshields,
and leaded gasoline.  We don't use them any more.  We got by with core
memory and punch-tape I/O, and those still work exactly as well today as
they ever did.  But we don't use them any more.  For decades, Detroit
used vacuum-mechanical cruise controls that they claimed would hold a
speed within -2/+5mph, on level ground, and in practice often closer to
-5/+15mph by the time the drum servo got a little bit worn or glazed.
Now, we build cars with digital-proportional cruise controls that'll
hold to within about +/-1.25mph.  Can you imagine what customers and the
automotive press would have to say now if you brought out a car that
went back to vacuum-mechanical cruise control and that level of ?

The mechanical-float resistive fuel guage is an obsolete technology that
we don't have to put up with any more.  We can do so much better now,
and have a more reliable, more accurate guage with no moving parts that
requires no components inside the tank exposed to fuel.

So why don't we?

Rhetorical question, of course.  I'm perfectly aware that the answer is
"Because auto manufacturers can still get away with selling float
resistive guages".  You can't see the fuel sender from outside the car,
so it's not a selling point, because no-one ever thinks of them when
they're buying a car.


> 6. If a housewife runs out of gas, and decides to walk to the gas station
>    and gets raped, murdered, or even mud spattered, a hot shot lawyer
>    will sue.

Which is going to have a better chance of being thrown out of court -
the lawsuit for the woman who ran out of gas exactly when the fuel guage
said she would, when the car had been blinking a red "LOW FUEL" warning
at her for the past 20 miles, or the lawsuit for the one who ran out of
the gas with the fuel guage still reading almost a quarter tank?


(Unfortunately, in the US court system, that answer isn't nearly as
clear-cut as it should be.  In the UK, if you tried to sue an auto
manufacturer because the fuel guage was accurate, they'd TOLD you the
fuel guage was accurate as a selling point on the car, and you knew you
were low on fuel but tried to push your luck anyway, the case wouldn't
make it past barrister's review; it'd be thrown out as a frivolous
lawsuit before it ever got to a judge.)


-- 
 Phil Stracchino                     Landline: 603-886-3518
 phil.stracchino at speakeasy.net         Mobile: 603-216-7037
 Renaissance Man, Unix generalist, Perl hacker, Free Stater