Not Logged In Log In   Sign Up   Points Leaders
Follow Us    10:00 AM

Message Forum - Read Message

Category: Fuel Economy > Topics Add to favorite topics   Post new topicPost New Topic
Author Topic: Last 1/4 in tank seems to go fast. Back to Topics
Terzo
Champion Author
Orange County

Posts:3,519
Points:730,290
Joined:Mar 2012
Message Posted: Mar 22, 2012 4:07:06 PM

Anybody else notice that the last 1/4 in their gas tank seems to burn up faster than at any other level? When I first bought my truck it seemed to be more consistent, but now I have to keep the tank at a higher level or I'll burn fuel too fast. You'd think with less weight to carry around that I'd be getting better gas mileage, but I'm experiencing just the opposite. Anybody got any ideas what's going on?
REPLIES (newest first) Topic is locked
sagnat
Champion Author Riverside

Posts:1,916
Points:983,900
Joined:Jun 2012
Message Posted: Jan 7, 2013 1:05:19 PM

Probably because the fuel gauges aren't linear but rather a best guess on how uch is remaining.
hornet17
Champion Author Vancouver

Posts:1,323
Points:440,865
Joined:Aug 2011
Message Posted: Jan 7, 2013 10:04:33 AM

inaccurate fuel gauge? Most of them are.
musicreporter
All-Star Author San Antonio

Posts:966
Points:667,140
Joined:Dec 2012
Message Posted: Jan 7, 2013 9:53:57 AM

yes
wlotocky
Champion Author Florida

Posts:1,051
Points:289,270
Joined:May 2010
Message Posted: Jun 15, 2012 1:04:50 AM

yup
Seamus4513
Champion Author Orange County

Posts:5,612
Points:1,150,430
Joined:Mar 2012
Message Posted: Jun 14, 2012 4:00:22 PM

I havent noticed. In my old ES, my avail fuel increased in hard right turns
minet
Sophomore Author British Columbia

Posts:150
Points:74,425
Joined:Jun 2012
Message Posted: Jun 11, 2012 9:16:51 PM

yeah the lower the level of fuel, the faster it burn out. i always fill up when its 1/2 tank. i get more milleage everytime.
nordlead
Veteran Author Syracuse

Posts:330
Points:161,140
Joined:Jun 2011
Message Posted: Jun 11, 2012 1:09:56 PM

when near empty, I can gain 1/8th of a tank just by driving up a hill :-D

Until (as mentioned below) there is a system to measure input and output of the gas tank no gauge will be very close to correct. I just watch my trip meter and reset it at every fill-up.
Jude23
Rookie Author Vancouver

Posts:36
Points:3,780
Joined:Jun 2012
Message Posted: Jun 10, 2012 10:12:49 PM

Yes! Drives me crazy too. I always gas up in the states and if I've not watched my amount of driving and am coming close to that 1/4 tank mark it's scary how fast it can plummet while I'm doing 110kph heading for the border! :)
prob52
Rookie Author California

Posts:1
Points:20,170
Joined:Jun 2012
Message Posted: Jun 9, 2012 7:54:44 PM

My gas light comes on when I have 50 miles left. I usually put gas in when the light comes on.
diesdown
Champion Author North Carolina

Posts:2,037
Points:981,315
Joined:May 2011
Message Posted: Jun 9, 2012 6:03:36 PM

That's because it most likely is NOT a full 1/4 tank......instrument measurements vary greatly.
vikings80
All-Star Author South Dakota

Posts:781
Points:110,065
Joined:Aug 2008
Message Posted: Jun 8, 2012 9:15:55 AM

quick
kxy4fw
Champion Author Denver

Posts:1,252
Points:285,430
Joined:Nov 2011
Message Posted: Apr 27, 2012 9:23:21 AM

reallllll fast!
dontuknowOH
Champion Author Ohio

Posts:3,966
Points:68,185
Joined:Aug 2009
Message Posted: Apr 26, 2012 12:53:01 PM

The shape and angle of the fuel tank is different on some vehicles,plus where it is placed for safety sometimes determins the capacity at different fuel levels.

Others have mentioned linear reading at the guage indicator may be designed a bit crude,that's often the case,same for sample readings by the ecu on more modern vehicles.

It's not good to always rely on the low fuel light before adding fuel myop.The other reason may be you just watch the guage more when running close to empty,concerned about the nearest location for refueling.Gas cans are no longer a cheap ticket item,but having one on board,well.....they are hard to borrow from strangers! LOL
JCLNC
All-Star Author Greensboro

Posts:917
Points:232,300
Joined:Jun 2011
Message Posted: Apr 23, 2012 3:57:40 AM

I try not to let my tank go below a 1/4.
cheapmonkee
Champion Author Portland

Posts:34,261
Points:3,949,885
Joined:Jun 2004
Message Posted: Apr 23, 2012 1:23:43 AM

I keep mine fairly full. The largest fill this year was 7.75 gallons. My tank is a little more than 12 gallons.
Z12
Champion Author Toledo

Posts:3,755
Points:982,845
Joined:Mar 2011
Message Posted: Apr 22, 2012 8:50:37 PM

Yes, it does
Titanic1985
Champion Author South Carolina

Posts:10,545
Points:1,009,620
Joined:Dec 2010
Message Posted: Apr 22, 2012 6:50:19 PM

Hello Terzo. I've read the posts on this thread and the conclusion of non-linear gas guages is correct. That said, there is another factor involved. Last year, I read an automotive article regarding gas guages and it is a no win situation for the manufactures. If a gas guage goes off full after just a few miles of driving, the driver feels the vehicle is getting poor gas mileage. If, on the other hand, the guage stays on full longer, that same individual thinks the vehicle gets great gas mileage. Since the guages are based on a float system in the tank connected to a variable resistor to the guage, the manufactures tend to keep the guage at full longer followed by a more rapid plunge to empty. It is, in reality, a marketing ploy and was well documented in this article using the same drivers and the same vehicles. I never thought of this issue until I read the article.
Tweak3D
Rookie Author Tacoma

Posts:34
Points:30,865
Joined:Jun 2011
Message Posted: Apr 20, 2012 9:42:27 AM

A linear fuel gauge would be nice, but isn't so easy to design and maintian between multiple lines of vehciles. This is because of the shape of the fuel tank changes making each fuel take require a unique calculation. Newer cars are better because they use a combination of the feed back from the fuel tank sensor along with fuel flow #'s from the injectors and can give us a fairly accurate idea of how we are doing.
JimBlake56
Veteran Author Akron

Posts:415
Points:111,590
Joined:Oct 2010
Message Posted: Apr 12, 2012 11:54:56 AM

Non-linear fuel gauge is pretty common.

Sometimes the divisions on the gauge are skewed to reflect that, for example the space between empty & 1/4 is big, then the space between 1/4 & 1/2 is smaller, etc. Sometimes 3/4 is very close to the top.

On some cars the gauge actually works that way, but the stylists have decided that it looks better if the gauge divisions are evenly spaced.
mnrick041
Champion Author Twin Cities

Posts:18,352
Points:2,146,635
Joined:Jun 2009
Message Posted: Apr 10, 2012 1:13:27 AM

I had a car once that seemed to stay at full for a long time, then it would drop, stay at about 3/4 for awhile and then it would drop like a rock. My car I have now shows me "miles to E" on a dash readout, that is a little more informative than the old gas gauges were.
13Octane
Champion Author Tucson

Posts:2,157
Points:360,765
Joined:Aug 2005
Message Posted: Apr 2, 2012 11:50:34 AM

nope
RacerGene
Champion Author Alabama

Posts:1,723
Points:372,025
Joined:Jan 2012
Message Posted: Apr 2, 2012 9:56:49 AM

just the meter that's not accurate
forresj
Champion Author Wilmington

Posts:6,653
Points:1,285,510
Joined:May 2005
Message Posted: Apr 2, 2012 9:10:01 AM

no i never let the tank drop below 1/4.
MertieMan
Champion Author Lexington

Posts:18,039
Points:3,674,160
Joined:May 2005
Message Posted: Apr 2, 2012 7:44:46 AM

You shouldn't let your tank get this low.
WEDDY
Champion Author Phoenix

Posts:6,649
Points:1,811,570
Joined:Oct 2009
Message Posted: Apr 1, 2012 8:03:32 PM

Yes.
Jescareno22
Veteran Author Toms River

Posts:303
Points:58,070
Joined:Mar 2012
Message Posted: Apr 1, 2012 7:32:19 PM

no
KansasGunman
Champion Author Kansas

Posts:22,106
Points:2,117,980
Joined:Oct 2005
Message Posted: Apr 1, 2012 6:09:43 PM

Wouldn't know...can't remember the lat time we let the tank get below half on any of our vehicles.
jamieg2012
Veteran Author Sioux Falls

Posts:286
Points:11,385
Joined:Jan 2012
Message Posted: Apr 1, 2012 1:43:34 PM

part of it is how much gas gets on the sensor for how full

as it moves you will go back and forth from reading empty to about half

that is what my car usually does and it is based of pressure caused by more fuel so the road grade changes to give you a hill that goes up some and it makes gravity pull all the gas back to the sensor and you read more than is there - only a level parking spot will give you the right reading since even driving changes how much pressure on the sensor since stopping and the gas will still keep going forward until it hits the front of the tank then settle back down
pacecar68
Champion Author Oakland

Posts:5,375
Points:1,125,085
Joined:Jan 2007
Message Posted: Apr 1, 2012 12:53:25 PM

you are gambling by letting your tank get below 1/4 a tank. the fuel is a coolant for the fuel pump. burn the pump up and you will be surprised at how expensive to replace.
DCD_Guy
Rookie Author San Francisco

Posts:68
Points:43,075
Joined:Jan 2012
Message Posted: Mar 27, 2012 3:05:45 AM

It's the fuel gauge designed like that, non-linear to emphasize the most
concerned area. Try a digital fuel meter, you will get linear readout.
The engine will not burn faster like you said. Let me know if you need
help to do the test with a good linear meter.
sluggopyle
Champion Author North Carolina

Posts:23,609
Points:1,076,110
Joined:Dec 2005
Message Posted: Mar 25, 2012 12:51:44 AM

=> You get the best gas mileage on a full tank and the last quarter tank does have a lower MPG than the 1st quarter mile if you went by your meter. <=

No. You don't. You're looking at a non-linear gauge; the "1/4" mark is not really 1/4; it's less. If the marks showed accurately how much gas was in there, they would not be evenly spaced. Conditions being equal, you get the same mileage with the first quarter as you do with the last-- it's just not telling you accurately where either one is.
Pucelle
Rookie Author Rochester

Posts:33
Points:120,540
Joined:Jun 2002
Message Posted: Mar 24, 2012 7:30:26 PM

You get the best gas mileage on a full tank and the last quarter tank does have a lower MPG than the 1st quarter mile if you went by your meter.

But if you go on a long trip on the highway using a full tank you will see that you get the same MPG through out the trip so it's just the meter that's not accurate.
greydog13
All-Star Author Iowa

Posts:767
Points:984,215
Joined:Feb 2011
Message Posted: Mar 24, 2012 7:09:13 PM

I don't generally let the tank get much below 1/2. I fill up more often but it does not hurt as much $$ when I do---
kxy4fw
Champion Author Denver

Posts:1,252
Points:285,430
Joined:Nov 2011
Message Posted: Mar 24, 2012 9:57:30 AM

Yup.
OceanArcher
Champion Author Mississippi

Posts:8,500
Points:1,999,995
Joined:May 2004
Message Posted: Mar 24, 2012 9:02:40 AM

Most gas tank metering systems are non-linear. They try to make it such that the gauge movement matches the shape of the tank, but darned few ever manage it. Until we get an integrated system that both measures how much fuel is pumped into the tank, and compares it with the fuel usage, then we will just have to accept there is a level of error in the gauge
gobux10
Champion Author Ohio

Posts:4,212
Points:886,680
Joined:Mar 2010
Message Posted: Mar 23, 2012 9:07:25 PM

Appears 2
13Octane
Champion Author Tucson

Posts:2,157
Points:360,765
Joined:Aug 2005
Message Posted: Mar 23, 2012 6:34:30 PM

really?
jes
Champion Author Pennsylvania

Posts:19,315
Points:4,109,295
Joined:Jun 2003
Message Posted: Mar 23, 2012 5:06:40 PM

Every vehicle I've owned has been like this. I just come to expect it.
Dennis783
Champion Author Des Moines

Posts:16,825
Points:3,455,145
Joined:Sep 2005
Message Posted: Mar 23, 2012 9:27:55 AM

I have noticed that on the fuel gauge. I ignore that and look at the fuel range display
gasmask78
Champion Author Virginia

Posts:4,856
Points:1,104,025
Joined:Sep 2011
Message Posted: Mar 23, 2012 12:53:03 AM

It's because most older cars have little weights in gas tanks.
gougedQC
Champion Author Montreal

Posts:5,686
Points:77,365
Joined:Apr 2008
Message Posted: Mar 22, 2012 7:30:30 PM

I've noticed this as well.. non linear measurement.. I think its a deliberate ploy by the car companies..all of them..

They know most people dont run to empty...but rather to perhaps a little under half..so they skew the readings to make you thing your going farther on your tank of gas..
rick_evans
Champion Author Boston

Posts:7,113
Points:1,796,030
Joined:Aug 2005
Message Posted: Mar 22, 2012 7:00:12 PM

Have you noticed that the first 1/4 tank takes much longer? Every car I've ever owned including my current 07 Corolla has had a non-linear reading fuel gauge which stays pegged at full for the first 50 to 80 miles while appearing to go fasted through the last 1/4 tank.
Topic is locked Back to Topics