I hate this fuel gauge!

flash7210 · **Posted:** Thu Jun 25, 2009 7:04 am

The low fuel light came on when heading to work this morning. I stopped
and put 10 gallons in the tank.
The gauge now reads 3/4 full!

ribbon · **Posted:** Thu Jun 25, 2009 9:09 am

fuel float?

chrispitude · **Posted:** Thu Jun 25, 2009 10:42 am

Probably normal behavior. This has to be one of the worst nonlinear fuel gauges I had to deal with in any vehicle. You get almost 100 "free" miles until the needle even modes away past full, but below 1/4 tank you'd better find a station soon. When towing, you'd best starting looking for a place to fill up once it gets below 1/2 tank...

- Chris

danoid · **Posted:** Thu Jun 25, 2009 11:01 am

Ditto that.
Full -> Half (indicated) = 14-15 gallons
Full -> Quarter (indicated) = 17-18 gallons
Full -> Empty (indicated) = 18-20 gallons

at least from what I see.

ac5501 · **Posted:** Thu Jun 25, 2009 11:07 am

If i don't shut off the engine when filling up, it really displays wrong. I'll put 16 gallons in and the gauge will show about 1/4 tank. After about 30 min of driving it slowly goes to where it should. If I turn the engine off before fill up, it behaves normally (well as normal as you can get for that gauge)

I don't know what they were smoking when they designed this gauge but I wish I had some.

Here's how mine works. (summer) - in the winter just shave about 20% off the numbers:

100 miles before rising above full: then....

90 miles (if I'm lucky - 100-110) to go from there to the 3/4 mark: then...

150 miles(if I'm really lucky) to go from there to the 1/2 mark

150 miles ( 170 if I'm really lucky) to go from there to the 1/4 mark

50 miles (sometimes less) to get from 1/4 to empty - I swear you can watch it drop from this point

from there I cant tell cuz I get way to scared when the needle hits empty and fill up (usually fill up at the 1/4 mark). But based on the amount I pump from the empty line, I'd say I have 60-100 miles left before running out.

danoid · **Posted:** Thu Jun 25, 2009 11:49 am

That kind of behavior is expected. There is a lot of filtering of the signal to avoid the needle bouncing up and down with fuel slosh (and provide data for the distance to empty calculation). Ever drive a riding lawn mower and watch that fuel indicator built into the cap? It bounces so much it can't be used while the mower is in motion - can't have that in a car. Turning the ignition off effectively 'resets' the signal filter (it's assumed during ignition that the vehicle isn't in motion = no fuel slosh).

It's not a trivial calculation / calibration effort. But it's also a deliberate decision to bias the indicated needle towards the full part of the gage. What probably happened is that most of the calibration effort focused on the gas (patooie) version and now that we're pushing nearly double the fuel economy (my 2002 3.7L averaged 15 mpg) the calibration is even more out of whack than intended. The same is also probably true for the EVIC displays of average mpg and distance to empty. Mine over report by about 10%.

*edit*
My AirLifts giving me a constant rear lift probably throw another wrench into the mix. Even at minimum air pressure the back end always rides higher than the front. This changes the fuel distribution in the tank front to rear and the float travel aint the same as stock.

linewarbr · **Posted:** Thu Jun 25, 2009 12:30 pm

I rarely turn off the engine while fueling, and I can look through the window and watch the gauge go all the way from empty to full. However I have had the same experience with the accuracy of the gauge. I can drive to and from work 4 times before I need to fill up. After the fourth trip, I am usually showing between E and 1/4 tank, but if I get out on the road on the fifth day my fuel light will be on before I go 25 miles.

I've often wondered about using the spare tire mount for an auxilliary fuel tank, particularly for a SVO fuel system.

Uffe · **Posted:** Thu Jun 25, 2009 2:35 pm

The gauge in the skoda is funny too. It doesn't move before I've covered about 230 miles, and reads half after 440 miles

I do use the TDI trick to keep the breather open while fueling. After filling it up I can see the diesel in the filler neck tube. Brilliant!

stoutdog · **Posted:** Thu Jun 25, 2009 3:14 pm

Okay, random side note... why on earth are a number of you people not turning your cars off while filling up? Maybe I'm missing something here, but all you are dong is successfully wasting fuel (and probably risking a fire or worse). May as well leave the car running while you go into Wendys.... You aren't driving the car, you aren't even inside of it - why is it on?

It makes no sense! Especially from those of you who are trying to maximize your mpg...

Turbo Tim · **Posted:** Thu Jun 25, 2009 3:25 pm

Filling a diesel while running is legal. There is no ignition source, no fumes as fuel is an oil. No way to start a fire.
It's nice getting into a nice cool area after fueling in 110* degree heat.

ac5501 · **Posted:** Thu Jun 25, 2009 4:13 pm

stoutdog wrote:

Okay, random side note... why on earth are a number of you people not turning your cars off while filling up? Maybe I'm missing something here, but all you are dong is successfully wasting fuel (and probably risking a fire or worse). May as well leave the car running while you go into Wendys.... You aren't driving the car, you aren't even inside of it - why is it on?

It makes no sense! Especially from those of you who are trying to maximize your mpg...

3 Reasons for me.

1) First of all, most of the time when I pull into a fuel station, I've been running the engine for a while, and the turbo needs to cool down - i dont have a turbo timer. So, I really don't want to just shut off the engine and let the turbo cook.

2)I know this does not make any sense, but I found that when making several stops (shopping for example). When I have to start and stop the engine, my fuel gauge drops faster then it would if I just let the beast run.

3)All the big rigs let their engines idle when filling. So as long as I get to fill up at the big kids pump, I'm gonna act like they do. Even if I am "just a little guy" in the diesel family

linewarbr · **Posted:** Thu Jun 25, 2009 4:19 pm

x2.

I'm more concerned about the life of the turbo and the starter - and the engine wear that comes from stopping then restarting an engine - than the lost fuel from idling while filling up.

vegiH · **Posted:** Thu Jun 25, 2009 4:25 pm

I drove OTR for many years,and let me tell ya, a diesel is a diesel,period.As a matter of fact on the long hauls one of the games we played was "find the diesel",it went like this,"Hey,joe,whatsyaknow.I see a diesel coming down the road,what color was it?"Or find how many diesel between point a and point b.My all time favorites was to "double tap the hazards" this means I flash my hazards twice,you slip in behind the trailer and catch a free ride down the road,It helps to have a CB,and also if I know its a Diesel,I double tap without CB,because 9 out a 10 they know the name of the game..................H

stoutdog · **Posted:** Thu Jun 25, 2009 6:11 pm

TurboTim - I live in AZ as well. Never noticed my old truck getting significantly hotter in the <5 minutes it took to fill up and pay for my 30 gallon tank.

ac5501 - 1) The only time you really have to worry about the turbo cooling down is when you have just pulled of the interstate. If you are just filling up after driving around town (35-40 mph), it shouldn't be that big of a deal. My family has been driving diesels for more than 15 years, never had a problem... 2) I think you can attribute that to the junky fuel gauge. 5 minutes of idle, even on a low-idle diesel, will use more fuel than a restart. 3) Bigrigs have a very different setup than our "little guys" and rarely are concerned with small variations in mpg. They are getting bad enough anyways...

linewarbr - Again, in 15+ years of driving diesels, we have never noticed undue wear and tear on the engine or the starter from turning off the vehicle at the pump. Think about it, how often do you start and stop your car every day? At most, 5% of that time is at the gas station... leaving it running in those situations isn't really going to make much of a difference.

Turbo Tim · **Posted:** Thu Jun 25, 2009 10:57 pm

Most of the time I shut down when refueling. However, when my wife is with me, I keep the ac on for her.
As all of the married folk out there know, if the wife is happy, everyone is happy.....

stoutdog · **Posted:** Thu Jun 25, 2009 11:30 pm

Turbo Tim wrote:

Most of the time I shut down when refueling. However, when my wife is with me, I keep the ac on for her.
As all of the married folk out there know, if the wife is happy, everyone is happy.....

I'm not married, but i can understand that! :lol:

I hate this fuel gauge!

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