Fuel Tank Capacity

[Larry Rogers]

Couple of questions about the fuel tank. First, how much does it really
hold? The book says 17 gallons. But when the gauge is on E and the little
gas pump lite is glowing, I only get about 13 gallons to fill it up. One
time (and I was sweating it) I drove until the gauge needle was past the E
and I put in 14 gallons. I checked the Owners Manuel and it says 17 gallons.
I also checked to see how much reserve capacity it has when the low fuel
lite comes on. The manual says "When the light comes on, put in gas." How
wonderful!!! Just the information I was looking for!! Nothing technical like
"You have two gallons remaining." Obviously the writers of the manual didn't
think I could cope with the overwhelming mathematical computations involved
in figuring out how far I could go on the remaining gas. Just put in some
more!

The reason this is somewhat important.... when I am traveling down the
interstate highway and the gas gauge is on E (it doesn't stand for 'Enough')
and the price at the next exit is $3.12 but the price at the exit fifty
miles further down is only $2.86, I would like to know that I can make the
extra miles. I get about 20 MPG, so if I have another 3 gallons in the tank
when the low fuel indicator comes on, then I could make it the extra 60
miles.

I drive a lot. I have about 211K on a '99 RX 300. When I can save about
twenty bucks each trip, you can begin to understand the economics involved.
And please don't tell me to get some tin-can gas squeezer. I drive through
orange groves and muddy cow pastures and along side soybean fields. This
thing has four wheel drive for a reason. And I use it. This ain't no Garage
Queen. But when people get in, they say it looks like it's new.

Anybody care to venture a guess about the fuel gauge? Or do I just put a
spare gas can in the back, drive it until it runs out, check the odometer
reading and go from there?

Larry
In the back yard, under the oak.

[Ray O]

Post by Larry Rogers
Couple of questions about the fuel tank. First, how much does it really
hold? The book says 17 gallons. But when the gauge is on E and the little
gas pump lite is glowing, I only get about 13 gallons to fill it up. One
time (and I was sweating it) I drove until the gauge needle was past the E
and I put in 14 gallons. I checked the Owners Manuel and it says 17
gallons. I also checked to see how much reserve capacity it has when the
low fuel lite comes on. The manual says "When the light comes on, put in
gas." How wonderful!!! Just the information I was looking for!! Nothing
technical like "You have two gallons remaining." Obviously the writers of
the manual didn't think I could cope with the overwhelming mathematical
computations involved in figuring out how far I could go on the remaining
gas. Just put in some more!
The reason this is somewhat important.... when I am traveling down the
interstate highway and the gas gauge is on E (it doesn't stand for
'Enough') and the price at the next exit is $3.12 but the price at the
exit fifty miles further down is only $2.86, I would like to know that I
can make the extra miles. I get about 20 MPG, so if I have another 3
gallons in the tank when the low fuel indicator comes on, then I could
make it the extra 60 miles.
I drive a lot. I have about 211K on a '99 RX 300. When I can save about
twenty bucks each trip, you can begin to understand the economics
involved. And please don't tell me to get some tin-can gas squeezer. I
drive through orange groves and muddy cow pastures and along side soybean
fields. This thing has four wheel drive for a reason. And I use it. This
ain't no Garage Queen. But when people get in, they say it looks like it's
new.
Anybody care to venture a guess about the fuel gauge? Or do I just put a
spare gas can in the back, drive it until it runs out, check the odometer
reading and go from there?
Larry
In the back yard, under the oak.

I do not have a definitive answer to your question, but I can tell you why
it is so difficult to provide a definitive answer. Fuel tanks are not
symmetrically shaped and the fuel gauge sender moves in an arc so the fuel
gauge appears to move more slowly at the top and bottom of its range of
travel. The low fuel light uses a sensor that sends voltage to the light
when the sensor dries out. The odd shape of most fuel tanks means that not
all of the fuel in the tank is useable or within the pickup area for the
fuel pickup.

I recommend that you do not allow your vehicle to run out of gas because the
fuel pump uses the fuel passing through it for cooling, and if it runs dry
often, the fuel pump may be damaged, or at least have its life shortened.
This possibility for damage to the fuel pump can also happen if the fuel
sloshing at the bottom of the tank causes the fuel pickup to suck in air,
causing drivability problems in addition to putting wear and tear on the
fuel pump. Driving with very little fuel in the tank also means that the
fuel pickup is more likely to pick up contaminants, water, or sediment from
the bottom of the tank, possibly causing problems with the fuel filter, fuel
injectors, and catalytic converter, and the extra air in the tank means that
there is greater chance for condensation to accumulate in your fuel tank.

I try not to run more than 20 or 30 miles on the highway once the low fuel
light is solidly illuminated to avoid the potential problems I listed above.
The cost of replacement parts can outweigh any savings realized from
stretching too far.

Another possible solution (albeit one that is probably a pain) is to stop
and get 2 or 3 gallons to get you to the station with less expensive fuel.

[Larry]

Yea, I'm a regular Nascar whiz at the ole splash 'n go! Most of the time
there is not a problem. But once in a while it would be nice to know how
much room do I actually have in this invisible envelope that I'm trying to
push.

Larry
In the back yard, under the oak.

[mcbrue]

If you would just stay on the nice flat hard cement thingines with
pretty little stripes and pictures and signs along the sides, you
would get a lot better milage. The Japanese have very cleverly
designed their trucks to run on the cement thingies which are called
roads. It is a well knows fact that very few vehicles of any sort get
stuck on roads, and the incidence of stuck vehicles is much higher
along-side places like orange groves, soybean fields, and cow, bull,
and steer pastures. Of course if you are out there next to a soy bean
field, there is probably a nice firendly farm house nearby. And you
could go up to it and ask the nice young daughter for some gas - well,
you could ask the nice young daughter for something or other, or you
could let the boyz in tha bak ask her.

mcbrue under the bridge in the trailer down by the river

[Larry]

I'll do my own asking, thanks. She might not appreciate the gang in the
back, not to mention the gangster in the front. Believe me, there is never
less than a half tank in this thing when I go on these "well maintained farm
roads.... why, I take the tractor through here all the time!" It is
precisely when I'm on the flat had cement thingines that it would be nice to
know about that idiot lite. Not that I'm idiot enough to trust it, but it
would be nice to know about how much fuel is left when it comes on.

The other way I always check is with the trip meter. That function is very
handy. I use the A trip meter for fuel mileage and the B meter for oil
changes. When I'm on the concrete, I watch the meter as well as the fuel
gauge. When the meter says two-fifty, the gauge will be registering empty,
and it will take about thirteen gallons. But if the tank does actually have
seventeen gallons, that would mean I have at least two usable gallons left
with maybe one to spare. Then I could make it to that next exit. But when I
have been out mashing cow pies, it doesn't matter what the trip meter says,
when the fuel gauge gets low, I fill it up!

Oh, well. I'll just keep doing it this way. Thinking about replacing this
thing anyway. All I have to do is figure out a way to lie about the mileage,
wax it up, and put it out by the big road with a sign on it.

I hear Studabaker is making a comeback. Some Canadian guy that made it big
on the internet is going to fulfill his fathers dream. Anybody know if they
have a four-wheel drive model?

Larry
In the back yard, under the oak.

[kitzler]

Post by Larry Rogers
Couple of questions about the fuel tank. First, how much does it really
hold? The book says 17 gallons.

While the book does state correctly the tank holds 17 gallons, I can
attest putting 16 gallons in my car, it is foolish to go down that
much. You may have impurities in the tank that usually settle in the
bottom and that even the fuel filter cannot remove.

Should any of that go into your injectors, you'll wish you had stopped
to fill up sooner. Lexus should state so in their literature, because
it is true the low fuel light comes on when you still have about three
or four gallons left in the tank.

/Nick

[Elmo P. Shagnasty]

Post by kitzler
While the book does state correctly the tank holds 17 gallons, I can
attest putting 16 gallons in my car, it is foolish to go down that
much. You may have impurities in the tank that usually settle in the
bottom and that even the fuel filter cannot remove.

Those impurities will be settled to the bottom whether the tank is full
or not. The screen keeps the big pieces out, and the fuel filter
catches the small pieces.

Low fuel doesn't change that one bit.

The "impurity" thing is simply an old wives' tale spread by people who
don't stop to think things all the way through.

[mcbrue]

I remember an old family tale about my grandad's model T - he had to
back it up one particular hill if it was low on gas because the drain
hole was in the front of the tank and if the gas all ran to the back -
well it wasn't good. But now they have this wonderfull little device
inside the gas tank. It is a squishable plastic container. As the gas
level gets lower, the plastic squishes around the remaining gas
forcing it out and you don't need to worry about how you drive up or
down hills. Of course if any of the assorted bits and pieces in the
tank are sharp enough, they will cut holes in the plastic and the
whole thing sort of gets really dodgy. You never can fill the tank up
with the stated maximum amount, because there is always some gas left
in the tank outside the plastic bag. So it might be time to have the
tank checked. I am sure your local stealership would be glad to check
it for free if you just explain it to them. Of course they may have to
replace the baggy and they would charge you for that.

I do remember one time in Utah driving out to the golden spike
memorial. Beautifull drive, but a bit long. So on the return trip, I
coasted down a lot of hills. But the rental car did have the plastic
baggy so I could at least go down forward. That sort of broke me from
pushing the empty sign on the dash.

mcbrue under the bridge down by the river in the trailer

[Ray O]

Post by mcbrue
I remember an old family tale about my grandad's model T - he had to
back it up one particular hill if it was low on gas because the drain
hole was in the front of the tank and if the gas all ran to the back -
well it wasn't good. But now they have this wonderfull little device
inside the gas tank. It is a squishable plastic container. As the gas
level gets lower, the plastic squishes around the remaining gas
forcing it out and you don't need to worry about how you drive up or
down hills. Of course if any of the assorted bits and pieces in the
tank are sharp enough, they will cut holes in the plastic and the
whole thing sort of gets really dodgy. You never can fill the tank up
with the stated maximum amount, because there is always some gas left
in the tank outside the plastic bag. So it might be time to have the
tank checked. I am sure your local stealership would be glad to check
it for free if you just explain it to them. Of course they may have to
replace the baggy and they would charge you for that.
I do remember one time in Utah driving out to the golden spike
memorial. Beautifull drive, but a bit long. So on the return trip, I
coasted down a lot of hills. But the rental car did have the plastic
baggy so I could at least go down forward. That sort of broke me from
pushing the empty sign on the dash.
mcbrue under the bridge down by the river in the trailer

There is no plastic bag inside passenger car fuel tanks.

[Elmo P. Shagnasty]

Post by Ray O
There is no plastic bag inside passenger car fuel tanks.

I don't know the material from which it is made, but the Prius sold in
the US uses a bladder inside the fuel tank.

[Larry Rogers]

Oh, dear. Someone else vindicating McBrue. And the full moon is on the rise.

Larry
In the back yard, under the oak.

[Ray O]

Post by Elmo P. Shagnasty

Post by Ray O
There is no plastic bag inside passenger car fuel tanks.

I don't know the material from which it is made, but the Prius sold in
the US uses a bladder inside the fuel tank.

I forgot about the Prius, but bladders are the exception, not the norm. ;-)

[stu]

I think you are referring to the bladder in the water tank in your well
water setup. No such bladder in your car.

Post by mcbrue
I remember an old family tale about my grandad's model T - he had to
back it up one particular hill if it was low on gas because the drain
hole was in the front of the tank and if the gas all ran to the back -
well it wasn't good. But now they have this wonderfull little device
inside the gas tank. It is a squishable plastic container. As the gas
level gets lower, the plastic squishes around the remaining gas
forcing it out and you don't need to worry about how you drive up or
down hills. Of course if any of the assorted bits and pieces in the
tank are sharp enough, they will cut holes in the plastic and the
whole thing sort of gets really dodgy. You never can fill the tank up
with the stated maximum amount, because there is always some gas left
in the tank outside the plastic bag. So it might be time to have the
tank checked. I am sure your local stealership would be glad to check
it for free if you just explain it to them. Of course they may have to
replace the baggy and they would charge you for that.
I do remember one time in Utah driving out to the golden spike
memorial. Beautifull drive, but a bit long. So on the return trip, I
coasted down a lot of hills. But the rental car did have the plastic
baggy so I could at least go down forward. That sort of broke me from
pushing the empty sign on the dash.
mcbrue under the bridge down by the river in the trailer

[Larry Rogers]

He ain't got no well. He gets his from the river.

Larry
In the back yard, under the oak.

[Charles Proctor]

Here's a variation. My 2007 ES-350 also has a digital "miles to empty"
indicator.
(1) How reliable is it?
(2) If it says 100 miles, do I really have 100 miles? Or are the last 50
miles up for grabs?

Charles

Post by Larry Rogers
Couple of questions about the fuel tank. First, how much does it really
hold? The book says 17 gallons. But when the gauge is on E and the little
gas pump lite is glowing, I only get about 13 gallons to fill it up. One
time (and I was sweating it) I drove until the gauge needle was past the E
and I put in 14 gallons. I checked the Owners Manuel and it says 17
gallons. I also checked to see how much reserve capacity it has when the
low fuel lite comes on. The manual says "When the light comes on, put in
gas." How wonderful!!! Just the information I was looking for!! Nothing
technical like "You have two gallons remaining." Obviously the writers of
the manual didn't think I could cope with the overwhelming mathematical
computations involved in figuring out how far I could go on the remaining
gas. Just put in some more!

[Ray O]

Post by Charles Proctor
Here's a variation. My 2007 ES-350 also has a digital "miles to empty"
indicator.
(1) How reliable is it?
(2) If it says 100 miles, do I really have 100 miles? Or are the last 50
miles up for grabs?
Charles

You probably have close to 100 miles, but if I were the driver, I would
start looking at around 75 to 50 miles to avoid the risk of damage to the
fuel pump. The fuel pump uses the fuel passing through it for lubrication
and cooling, and if it is run dry, the fuel pump's life can be shortened.
Since you are going to need the fuel anyway, might as well get it before
problems arise.

[Larry]

Ray O says...... "The fuel pump uses the fuel passing through it for
lubrication and cooling, and if it is run dry, the fuel pump's life can be
shortened."
Question.... does the fuel pump keep on running after it senses that there
is no more fuel? Wouldn't the engine quit and therefore the fuel pump would
quit running? When I switch on the car, the fuel pump primes, the ignition
sets up to fire, and when I turn the switch fully on, the car starts. If it
runs out of fuel, does the fuel pump keep on pumping even after I turn the
switch off? Even if I don't turn the switch off, doesn't the pump have a
safety override? Why should I be concerned about damaging the pump when I
run out of gas?

Larry
In the back yard, under the oak.

[Ray O]

Post by Larry
Ray O says...... "The fuel pump uses the fuel passing through it for
lubrication and cooling, and if it is run dry, the fuel pump's life can be
shortened."
Question.... does the fuel pump keep on running after it senses that there
is no more fuel?

The fuel pump does not have any sensors - that is, it cannot detect the
presence of absence of fuel flowing through it.

Wouldn't the engine quit and therefore the fuel pump would

Post by Larry
quit running?

Yes, if the engine is fuel-starved, it will stop, and the fuel pump will
stop when the crankshaft stops turning.

When I switch on the car, the fuel pump primes, the ignition

Post by Larry
sets up to fire, and when I turn the switch fully on, the car starts.

When you switch the ignition to the on position, the fuel pump does not
prime. The fuel pump will run when the crankshaft is turning, either from
the starter or from running.

If it

Post by Larry
runs out of fuel, does the fuel pump keep on pumping even after I turn the
switch off?

If the ignition switch is off, the fuel pump will not operate.

Even if I don't turn the switch off, doesn't the pump have a

Post by Larry
safety override?

No, because the designers assume that the driver does not wish to be
stranded and will fill the fuel tank before it runs dry.

Why should I be concerned about damaging the pump when I

Post by Larry
run out of gas?
Larry
In the back yard, under the oak.

You should be concerned about damaging the pump when you run out of gas if
you do not wish to have to replace it because it is prematurely worn out
from having been run dry.

When you run a car completely out of fuel, the engine will start to misfire.
On a single-cylinder engine like a lawnmower, a misfire probably wouldn't
hurt anything, but on a multi-cylinder engine, misfires tend to put uneven
loads on the crankshaft and bearings, which may not be catastrophic, but not
good either. Also, misfiring can damage the catalytic converter. An overly
lean fuel mixture will raise exhaust temperatures, which raise NOx
emissions, and the unburnt fuel from misfires can coat the catalyst in a
converter, preventing it from working.

Running the tank completely dry probably will not cause catastrophic or
sudden fuel pump or catalytic converter failure, but they may fail at 70,000
or 100,000 miles instead of lasting the life of the vehicle.

[Charles Proctor]

Everyone,

Your responses were just what I was hoping for. I do not intend to cut it
too close but wanted to understand the instrument.

Typically, I have been refueling when the fuel gauge indicates 1/4 tank, but
I have not let the miles-left indicator go below 100.

Charles

[Ray]

On Sun, 22 Jul 2007 07:05:01 GMT, "Charles Proctor"

Post by Charles Proctor
Here's a variation. My 2007 ES-350 also has a digital "miles to empty"
indicator.
(1) How reliable is it?
(2) If it says 100 miles, do I really have 100 miles? Or are the last 50
miles up for grabs?
Charles

I have a 2000 Avalon with similar indicator. Mine seems to read 0
miles to go with about 2 gallons of gas left. You can determine this
by filling when it says 0 miles left and subtracting gas to fill from
gas capacity. In my case this is 16.5 gallons and 18.5 gallons. Once
driving through Death Valley the digital indicator read 0 about 50
miles from the closest gas station. When I filled up it took close to
the indicated 18.5 gallons.

[unknown]

Post by Ray
On Sun, 22 Jul 2007 07:05:01 GMT, "Charles Proctor"

Post by Charles Proctor
Here's a variation. My 2007 ES-350 also has a digital "miles to empty"
indicator.
(1) How reliable is it?
(2) If it says 100 miles, do I really have 100 miles? Or are the last 50
miles up for grabs?

I understand what you're trying to accomplish though this is terribly bad
practice. As you get to the bottom of your tank the fuel pump is sucking
in the sediment in the tank which normally goes to the bottom. It's risky
and could cause engine malfunction, fuel pump (and filter) malfunction or
other bad things to happen.

We had a '93 Lincoln Town Car and one time travelling very late at night
nearly ran out of gas because of our own stupidity in misperceiving the
fact that we were entering a very long stretch of desolate highway. When
we finally found fuel the digital gauge said we had 8 miles left. The tank
capacity was rated at 20.6 gallons and it took 19.9 gal to fill it. I
interpret that to imply the Lincoln gauge as being quite accurate.
However, I later found out that this "Miles left until empty" is actually
a dynamic number that is re-calculated every time you fill up and press
the reset button. It knows how far (# of miles) you went before refilling
and it knows what position the fuel gauge float was at immediately before
you refilled and then extrapolates from there. Ergo when you first start a
long road trip after months of in-town driving, your initial "miles until
empty" display is apt to be very inaccurate toward the plus side (more
fuel available than claimed). However, after several hundred miles of
driving and a couple of fillups the same display is apt to be more
accurate... until you start in-town driving again.