TSB Released on Fuel Gauge Innacuracies

By itself, running out of fuel is not a problem. However, you could run the SOC down too far, and if you do run it down too often, you can shorten the life of the battery.

 

Cool, but does anybody know what is the travel/time/distance supply is on the SOC?, or do you just have to watch the little bars? I'm sure driving style affects the distance you can go, but somebody might have an ROT (Rule of Thumb)

 

shulmda:

I too live in CT and have had my car since Dec 30th.

What I have noticed about the fuel tank/ gauge is the following:

Cold Weather will do the following:

1- Shrink the bladder, or not allow it to expand to 11.9 gal capacity. Toyota even states you can have over 1 gallon less available space for fillup in cold weather.

2- The gauge I believe will react not only to consumption, but will also react to the ambient air temperature. Therefore I believe this is why people get 8-9 gallons when the car is screaming "Add Fuel" I have seen where the cold weather makes the gauge less accurate and it errs on the side of cuation.

3- Variations in temperature exacerbate the accuracy problem. I had a couple of tanks where the temperature was getting into the upper 50s and both gas mileage and accuracy of the fuel gauge were improving. Recently I started getting almost 50MPG and the temp was about 50, only to see the temp go back below freezing, mileage drop to the low 40's and the fuel gauge drop bars almost before my eyes.

I can't wait for the warm weather both to stretch out a tank based on performance and to have better accuracy.

 

MSS:
Thanks for the info. I knew that the cold weather could shrink the bladder size (i read that here) but I must have missed the fact that it can be as much a 1 gallon. I haven't run it to empty because I am too much of a chicken. I ran out of gas once in a really desolate place and I vowed never to do THAT again.
I am beginning to wonder if the introduction of the bladder on the US models was such a good idea. I may be wrong, but it seems like they don't have the bladder outside of the US. I wonder why.
I know that a bladder is theoretically safer and can help reduce emissions, but I am not very convinced about that. Except in the movies, explosions from gas tanks are very rare (though not impossible, please don't flame me) and my VW has a simple flap that opens and closes when you insert the fuel pump and that seems like a pretty good system to me.
I would really like to have that extra 1.9 gallons to use. I wonder if it is possible to have the bladder removed?

 

Toyota put the bladder in the Prius in North America for pollution control. I doubt you could legally remove it.

 

<div class='quotetop'>QUOTE(jkash\";p=\"70364)</div>

Well, while probably not technically legal according to the EPA, I doubt the state inspection stations are going to check to make sure you still have one in the tank. I myself have wondered if it would be possible to fit an overseas fuel tank assembly onto the US prius and whether it would work with the
US computer. It hasn't been enough of a problem for me though to justify the time or expense of looking into it further. I suspect it could also cause warranty coverage problems if Toyota discovered it.

 

I just bought my sandstone package 6 2005 Prius
on April 7th. It had just come off the truck and I
love it!!
I am too noticing the gas gauge is weird. I park it
outside and our temps here in Eastern Kentucky have
been around 35 degrees overnight and high 50's to
lower 60's in the daytime.
The low fuel flash came on at 383miles with an
average of 51mpg. So I went to the gas station
and it clicked off at 8.1 gallons.
It did the same thing the week before but only let
me put in 7.6 gallons.
When the weather was above 65 degrees daytime
it would flash when I needed to put in 9.6 gallons.

 

Great read!

My Prius falls into the range for the filler tube. I don't think I'm going to do it simply because what it boils down to is simply whether your fill up now versus a little later. If I can only get 8 gallons into the tank, fine. It's not going to cost me any more or less.... (unless, of course you want to re-factor and start arguing stopping for gas more frequently than actually required wastes MORE fuel... I hate to say it, but I don't care to be THAT efficient! lol )

 

well you could also argue that extra gas weighs more and lowers your mileage too

 

I had this TSB done in January 05 and it accomplished exactly nothing in terms of gas gauge accuracy. I had both parts done. In cold weather I could put no more than 6 gallons in and rarely could go over 300 miles on a tank before the last bar started blinking. The tech tells me Toyota deliberately calibrates the gauge to blink at 8 gallons. That seems to be the case in warm weather, but this winter, well, it would have been nice to have gone as far as 8 gallons should have taken me.

The thing the TSB did do to my car was that now the dashboard is loose. When I go over a bumpy road the back end of the dash (nearest the windshield) bounces up and down and with it the instrument panel. I brought it in twice to be repaired and the second time the replaced the entire top dash panel with its cheap plastic clips. No change. At least everything works: speakers, MFD, lights, etc.

I've scanned this thread and seen no mention of this. Anyone have this happen?

Susan
04 silver BC
24700 miles

 

I've been on this board since Jan of 2004 and I can't remember anyone saying the dash was loose after the fuel gauge TSB. I'm afraid if I was you the dealer would really be wondering why I was setting up my tent in their show room, but I'd be living there until it was properly fixed. Sorry I can't offer more but it's obvious that they are missing something on how to reassamble the dash.

 

<div class='quotetop'>QUOTE(efusco\";p=\"35219)</div>

me, too, Evan! it'll be a good test for me, though, because i've been topping off pretty much right up to the filler neck for the past 4000 miles... and with no spit-back at all. if i can get more fuel in the tank, i'll be pleasantly amazed!

 

I rented a Prius to test drive it for a day. That was essentially a brand new car with only 230 miles when I picked it up, and the fuel gauge was at 50%. After 150 miles, the gauge was at 25%. I added 2 gallons and drove it for a bit -- no change in the fuel gauge reading. Added another gallon, and still no change.

Is this a real problem, or was I supposed to push some buttons to reset it? The lady that handled the rental return didn't know.

 

It's a matter of opinion whether it's a problem or merely a trait, but the Prius gas gauge usually doesn't reset unless you add three gallons. I think it's even mentioned in the manual.

I never thought about this at $2/gallon, but as prices rise, someday I might not have the ready cash to put in three whole gallons!

 

Thanks for the response. It's not a big deal if that's the case. I normally wouldn't bother refilling only 2-3 gallons, but I just had to refill it enough for the rental return. Still odd behavior, though.

 

I never thought of that. That could cause an issue with rentals if you happen to only drive the car for 150 miles or so from last fillup before returning the car, refill and get no change to the gas guage. Then they charge you for refilling the car.

 

They couldn't charge you for much - they'd still have gas spilling out of the tank almost as soon as they started to fill it!

 

I had my worse tank in a long time this last few weeks. It started out bad. First bar went out at 75 miles. It is usually a little over 100 miles. I had two bars when I started up tonight, and it went to 1 bar blinking as soon as it started. I got gas about one mile from the house. I was only able to put in 7.29 gallons. It was colder than it has been, 54 degrees on the display, but that's not real cold. I guess I could still ask if I could get the fix, but I am loathe to do so. Doesn't seem like a good idea to take the car apart just to get two more gallons of gas in it.

 

time to check other things like tire pressure, air filter, and remember that your now well into winter gas down there and other things like rain could also cut what you normall see.

 

We've been having similar issues with our Prius. Since colder weather finally hit the southeast, our fuel milage has dropped. I've thought that it's probably the fact that the engine runs more in cold weather to keep the heaters running and the engine warm.

We've always had this problem of getting to the last bar of fuel, refilling to full and only being able to put in about 8.5 gallons of fuel. The last time I checked, the '05 Prius had an almost 12 gallon fuel tank. That's leaving 3.5 gallons of fuel...or another 175miles of distance. We have been getting ready to get a small 3 gallon fuel can, and run the car to empty just to see how much fuel the Prius can really take in. :angry: