100+ miles and No change on Fuel Indicator

[GreenSpeed]

Hi All,

I've had some weird things happen to me on a semi-recent trip back from Las Vegas. Basically i've driven to and from San Franciso to Las Vegas a couple of times in the last few months. On my 2nd trip back from Vegas (return leg) i noticed something really weird. See if any of you guys out there can make sense of this.

-Filled up tank per normal (Prior to leaving Vegas)
-Fuel indicator read as 'Full' (All bars fully lit)
-For first 2 hours (about 170+ miles) that i drove there was no change in the indicator
-After a total of 4 hours (253 Miles) the fuel indicator only had 1 bar gone (MFD stated i'd driven 250++ miles) already (Shouldn't that have read to be half-empty?)
-Near a total of 380++ i suddenly noticed i'd dropped down to 1 bar left. ('Add fuel' indicator on MFD came on)

I've not experienced this on my normal daily commutes and i'm not quite sure what to think. I just thought i'd through it out there and see if anyone had the same experience.

(The temp was hot and i don't drive like a crazy person...average speed was about 70+, average fuel economy was 42-47 MPG on the highway)

Cheers!

[Kolisar]

<div class='quotetop'>QUOTE(Green Speed @ Aug 4 2006, 07:04 PM) [snapback]297944[/snapback]</div>

Hi All,

I've had some weird things happen to me on a semi-recent trip back from Las Vegas. Basically i've driven to and from San Franciso to Las Vegas a couple of times in the last few months. On my 2nd trip back from Vegas (return leg) i noticed something really weird. See if any of you guys out there can make sense of this.

-Filled up tank per normal (Prior to leaving Vegas)
-Fuel indicator read as 'Full' (All bars fully lit)
-For first 2 hours (about 170+ miles) that i drove there was no change in the indicator
-After a total of 4 hours (253 Miles) the fuel indicator only had 1 bar gone (MFD stated i'd driven 250++ miles) already (Shouldn't that have read to be half-empty?)
-Near a total of 380++ i suddenly noticed i'd dropped down to 1 bar left. ('Add fuel' indicator on MFD came on)

I've not experienced this on my normal daily commutes and i'm not quite sure what to think. I just thought i'd through it out there and see if anyone had the same experience.

(The temp was hot and i don't drive like a crazy person...average speed was about 70+, average fuel economy was 42-47 MPG on the highway)

Cheers!
[/b]

I have the same problem. You are not alone.

[DaveinOlyWA]

i have had similiar weirdness although not that extreme. seems to happen mostly on longer trips @freeway speed.

have gotten home with 5 bars only to get up the next morning and have 6. to be honest with ya though, since getting CANVIEW, i really dont track bars anymore. did notice that on my current tank (378 miles @63+ mpg) that first bar disappeared at 150 miles, the 2nd at 165 miles...go figure

[seasalsa]

And you wonder why we call it the GUESS Guage?

[richard schumacher]

Yep, it's nonlinear, and it doesn't behave the same way each time. But it *does* know when the tank is nearly empty, so always buy gas ASAP when the last pip starts flashing. Prudent drivers do so before that point.

[BVISAILMAN]

I had the same problem driving ona 150 mile trip on the return I had 6 bars left when I started and drove about 90 miles and it dropped to 5, before too long the last bar was blinking and I actually ran it dry.....I was able to creep along the highway at about 50MPH for over two miles strictly on Batteries..NOw I make it a habit to fill up when there are three bars left.

[nerfer]

<div class='quotetop'>QUOTE(Green Speed @ Aug 4 2006, 06:04 PM) [snapback]297944[/snapback]</div>

(The temp was hot and i don't drive like a crazy person...average speed was about 70+, average fuel economy was 42-47 MPG on the highway)
[/b]

Was the temperature cool when you filled it up (like in the morning in the desert)?
You probably put dense fuel in the gas tank, which then expanded in the heat during the day. I noticed this the last couple weeks, I filled up on a cool day, then we got the heat wave and I stayed on full for over a week (140 miles, where normally it's about 80 miles before the first bar goes way). Then when the weather cooled a bit I started going thru bars every 30 miles, as I presume the gas cools (maybe the bladder too, not sure how that fits into the picture, but just the gas expanding/cooling makes sense in my mind, so why confuse things? )

My computed mileage was below normal too because I was probably able to put in more gas than normal. So this fill-up should be nice, I'm thinking.

[Starfall]

<div class='quotetop'>QUOTE(nerfer @ Aug 7 2006, 04:58 PM) [snapback]299270[/snapback]</div>

Was the temperature cool when you filled it up (like in the morning in the desert)?
You probably put dense fuel in the gas tank, which then expanded in the heat during the day. I noticed this the last couple weeks, I filled up on a cool day, then we got the heat wave and I stayed on full for over a week (140 miles, where normally it's about 80 miles before the first bar goes way). Then when the weather cooled a bit I started going thru bars every 30 miles, as I presume the gas cools (maybe the bladder too, not sure how that fits into the picture, but just the gas expanding/cooling makes sense in my mind, so why confuse things? )[/b]

Interesting explanation, Nerfer, & probably why PriusChat has been getting so many posts lately about the gas gauge being inaccurate.

It's rare (let's hope, at least!) to have a heat wave like we've had (in the whole nation) but perhaps, when we do, he had better all be extra careful about NOT trusting the gas gauge.

[dmckinstry]

<div class='quotetop'>QUOTE(richard schumacher @ Aug 5 2006, 01:20 PM) [snapback]298326[/snapback]</div>

Yep, it's nonlinear, and it doesn't behave the same way each time. But it *does* know when the tank is nearly empty, so always buy gas ASAP when the last pip starts flashing. Prudent drivers do so before that point.
[/b]

Even when it starts flashing isn't a very great indicator.

I know I've driven at least 30 miles after it's started flashing in the past, but about a month ago, it started flashing just after leaving the last gas station. The next one was about 15 miles ahead, so I proceeded. It ran out of gas after about 10 miles. I drove on the batteries about two miles 'til it gave up completely (on an uphill).
The temperature was close to 100 F, but luckily I got a ride. The gas station was about 3 miles away. I got a gallon of gas, got a ride back to the car, added the gas and drove to the station for a complete fill up. The total to complete the fill was 10.099 gallons. That's counting the 1 gallon already added.

Now it shouldn't have run out with about 1.5 gallons still in the car, but maybe it was because it was low and I'd been on a lot of hills. I'm guessing it shut down completely to prevent the the fuel injectors from running dry, but I don't know.

Anyway the gauge is definitely non-linear. A lot of times I do go 100 - 150 miles before the 1st bar disappears. It usually seems about right when it gets to the half tank level, but is again non-linear toward the bottom of the tank.

Dave

[DaveinOlyWA]

<div class='quotetop'>QUOTE(nerfer @ Aug 7 2006, 02:58 PM) [snapback]299270[/snapback]</div>

Was the temperature cool when you filled it up (like in the morning in the desert)?
You probably put dense fuel in the gas tank, which then expanded in the heat during the day. I noticed this the last couple weeks, I filled up on a cool day, then we got the heat wave and I stayed on full for over a week (140 miles, where normally it's about 80 miles before the first bar goes way). Then when the weather cooled a bit I started going thru bars every 30 miles, as I presume the gas cools (maybe the bladder too, not sure how that fits into the picture, but just the gas expanding/cooling makes sense in my mind, so why confuse things? )

My computed mileage was below normal too because I was probably able to put in more gas than normal. So this fill-up should be nice, I'm thinking. [/b]

sounds plausible... aint it nice to get so much return from the little expansion that the gas goes thru that its noticable??

love my Prius!!