gas gauge reading

The newer cars have a somewhat more accurate method
of measuring gasoline usage, but it is far from perfect.

Older cars had some version of a float in the tank and its
position was estimated by a potentiometer.  It was only
indicative and was not very quantitative.

The newer ones take measurements based on the fuel
injector operation.  More accurate, but not great.

For your car, fill it up, drive a number of miles and then
refill the tank.  It isnt perfect either, but will be a heck of
a lot more accurate than what you are trying to do,.

No.  All you can do is fill your tank up every day and check how much gasoline
has gone into it to make it full.

The gas gauge is only there to keep you from running out of gas, it's not
anything even remotely approaching linear or consistent.  It doesn't have
to be.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

On Fri, 03 Jun 2011 11:35:40 -0400, Scott Dorsey wrote:


But not every day. I generally let it go 150-200 miles to get an accurate
reading.

Don't ask me why, but filling it every day give me a lower reading than
going a couple hundred miles. Especially if I'm doing short trips.

I notice on weekends, when I rarely venture more than 5 miles from home,
mileage on my '89 Mazda 626 is ~28-30. During the week, when I drive 20
miles or more at a clip (over the same type roads, not the highway) I get
31-33.

On 4/06/2011 12:02 p.m., Hachiroku ��ロク wrote:

Cold starts and short trips use a lot of gas

--
A bus station is where a bus stops. A train station is where
a train stops. On my desk, I have a workstation.

cpliu wrote:

Your gas gauge is not linear.
To go from full to 3/4 full will likely take 12 gallons
and from 3/4 to empty will take 6 gallons, leaving
2 gallons in reserve at empty.

cpliu wrote:

A fuel gauge is not useful for that purpose.

Fill tank, record mileage.
On next fill, note fuel volume used and distance traveled.

If one keeps a simple log, any errors get smoothed after
more fill iterations

--
Andrew Muzi
  <www.yellowjersey.org/>
  Open every day since 1 April, 1971

AMuzi wrote:

    I would add that, since this incarnation of the Camry is prone to
filler pipe and vapor recover canister problems, you don't actually fill
it completely. Just wait until you hear the sound of the air rushing out
of the filler change pitch, and stop right there. Again, once you get
the hang of it any errors will average out over time.

On 6/3/2011 3:36 AM, cpliu wrote:

Your gas gauge gets more responsive towards the bottom of the tank.
Designing the gauge like this will give you a better idea of how much
gas is left in your tank.

My 2006 Hyundai has a resetable trip calculator that gives MPG reading.
I get around 14 MPG because my workplace is about a mile and a half
away. On long trips, I can get 24 MPG easily. It also gives average
speed. Mine is 14 miles per hour - seriously. :-)

90552904e112@32g2000vbe.googlegroups.com:


You cannot use the gas gauge as an indicator of mileage except in the
broadest, crudest manner (as in, "Am I going to run out of gas in the next
few minutes?").

The gas gauge employs a float that bobs up and down on top of the gas in
the tank. The float is connected to a lever that moves a contact back and
forth on a potentiometer (a special resistor). The changing location of the
contact results in a varying electrical current that is interpreted by the
gas gauge as a particular needle-reading.

As you drive, your gas is sloshing all over the place in the tank, and that
little bobber is bouncing all over the place like a pirate ship in a storm.
That's a problem. Left as-is, the bobber would cause your gas gauge needle
to also bounce all over the place. How automakers fix that is to install
some special electrical components in the circuitry. These components damp-
out most of that bobbing, so instead you see a s-l-o-w and steady change up
or down in the condition of the gauge needle, these changes corresponding
to you going up and down hills, or around corners.

When those damping components fail, the gas gauge turns into a weebly-
wobbly, bouncy-flouncy, wiggly bunch of useless fun, readable only when the
car is completely motionless and level. You come to appreciate the damping
when it's not there anymore.

If you want to accurately record your gas mileage, ignore that gas gauge
entirely. AMuzi has the correct idea, so see his message.

--
Tegger

Thank you all for the information. I'm trying to figure out a way to
make a pretty good guesstimate on how much gas has been used and left
by looking at the location of the needle. It looks like I'm not going
to reach a very accurate reading.

I calculate my MPG every time I fill up the gas tank (BTW, my 1994 4
cyl. is  a little over 40mph highway at 60MPH, 25 o 27 mph city at
earlier traffic time). I also made a record on the location of the
needle before adding the gas and after adding the gas.
Based on my record of before-and-after needle positions, I estimated
the following
empty to (0) =  ~2 to 2.5 gallons
(0) to (1) = ~2 gallons
(1) to (2, mid point) = ~4 gallons
(2) to (3) = ~ 6 gallons
(3) to (4) = ~ 4 gallons
2 more gallons you can add after it reaches the top.

Because I can never tell accurately when it actually reach each scale,
my numbers are probably off.

On 6/3/2011 10:22 PM, liu wrote:

Like others said, forget the gauge- use post-it notes or the trip
odometer, if you have one. Run it near empty, record the miles on the
clock. Run it near empty again, and record the miles again. The
difference is your maximum miles before you start looking for an open
gas station. Fill it every time, and record the miles every time. When
the odometer says you are getting near your empty point, fill up.  I
tend to top off when the gauge gets below half, in case price spikes,
and so I don't have to think about it. That, and $60+ fillups depress
the hell out of me. :^/

--
aem sends....

aemeijers wrote:

    Just a warning to all those Camry owners out there who are still
filling the tank completely to calculate fuel economy: the vapor
recovery system is likely to fail, and the filler pipe start leaking.
After battling these issues for several years we now just fill it
*almost* all the way. Problems solved. You can prevent them the same
way. You don't get an exact fuel economy reading, but if you already
know what the car averages, you can use the odometer to make sure it
hasn't suddenly started guzzling gas.

Hasn't this been the case for just about every car made since the late
eighties?  It's not anything specific to the Camry.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

0) to (1) = ~2 gallons

WOW US$60 to fill up if I read that correctly.
What a bargain.

I have a 1995 4 banger. Had it since new. 105.000 miles.
15 Gallon tank , so that's 15 X 4.5 for litres.
1 litre =  GB£1.35 = US$2.16
15 gallons = 67 litres.
Fill up costs  GB£91 =  US$145.

What can I say but  ***********************

Johnny UK

Tegger wrote:


Yup. It is even dumber to use dipstick measurements to calculate oil
consumption.


Well if that were the problem you could just
park the car on level ground when you need to get a good reading