gas gauge inaccurate

Welcome to the Priuschat forum's favor subject. The bladder.

As to the 42mpg in the cold, you will love it going up around 50mpg during the summer. There are people with less mpg in sub-zero weather. You probably did better because of the long commute.

 

My daily commute is about 100 miles round trip, and my refueling policy is to always fill up at the station 5 miles from my house. Sometimes this means that I put on close to 90 miles after the last box starts flashing, and I haven't had any problems--even in winter with 45mpg. I fill up the tank with 7-9 gallons and console myself with the notion that I still probably had plenty of fuel remaining. That said, some people have reported running out of gas fairly soon after the warning, so no promises.

Check out the posts on winter fronts and grill blocking. Some people have claimed rather remarkable improvements in cold weather milage. I tried it for the first time yesterday, and initial results are promising--a jump from 45mpg to 50mpg at 20F. Now that the temp is up in the 40s I'm seeing 55mpg for the first 50 miles--I haven't seen milage that good since summer, so I think it's worth trying.

 

Con, I thought the same thing about my Prius. After the gauge started blinking, I would fill up with 9 gal and think I had 3 left......wrong! Fortunately I haven't run out of fuel yet but I'm not going to push my luck. Try filling on the slowest setting on the pump nozzle. Any body have other suggestions for this?

 

<div class='quotetop'>QUOTE(conversion02 @ Feb 19 2007, 10:18 PM) [snapback]393079[/snapback]</div>

You are not the only one. Mine is also 3 weeks old and I filled up for the first time yesterday in 5F temps. I was shocked when the pump stopped at 7.5 gallons. I think the bladder stretched a little bit from the weight of the new gas because it only took 2 miles before the first pip was gone. I expect a larger tank in the summer and I hope it gets stretched out enough in the warmer temps to have a larger tank next winter too.

 

<div class='quotetop'>QUOTE(efusco @ Feb 19 2007, 10:30 PM) [snapback]393084[/snapback]</div>

Evan, when you say that the gas is difficult to access do you mean for the gas engine to access? Reason I am asking is that I had exactly the incident occur to me that others have referred to. A few weeks ago I had the blinking single bar for a couple of days on a weekend when I was doing limited driving and was intending to fill-up at the end of the weekend before going to work on Monday. My total mileage on the tank was at about 350 miles and with MPG at about 41 I thought I still had another 50 miles to go. Well to my surprise on the way to the mall on that Sunday up comes the Xmas tree on the dashboard and all of a sudden my acceleration is very limited and at first I didn't connect but then checked the Energy screen and battery was almost down to zero and it dawned on me that I was out of gas. Fortunately the small remaining juice in the battery allowed me to get to a gas station, filled up (10.2 gallons) and everything was back to normal. With at least another gallon of gas left and based on your comment Evan does that mean that the last gallon or so was really not accessible - it was cold, temp in the teens.

 

<div class='quotetop'>QUOTE(rohlrogge @ Feb 20 2007, 06:39 AM) [snapback]393196[/snapback]</div>

Yes, he means there is capacity in the tank that can't be used, especially in cold weather.

Tom

 

<div class='quotetop'>QUOTE(conversion02 @ Feb 19 2007, 10:18 PM) [snapback]393079[/snapback]</div>

I bought an 06 Prius. First trip we took was about 600 miles with an average of 49 MPG in interstate, secondary roads and hilly terrain. Boy were we excited. But as the mileage grew, the MPG fell to about 37-39 MPG. Now that the weather is bitterly cold and we have lots of snow on the roads, my display today shows I've driven 42 miles and the average is 23 MPG. I cannot get obsessed about the mileage but I am amazed with the many posts relating MPGs in the hi 40s, mid-50s, and some 60s and 70s. I was struck by a recent comment asking if it possible there are two types of Prius' - those that meet and exceed the EPA ratings and those like mine that simply get better mileage than, say my former Dodge Grand Caravan, which I turned back at the end of the lease and sold stock to buy a Prius. If I'm not getting the over-the-top mileage, at least I have a vehicle that is friendly to the environment and actually quite a lot of fun to drive. Maybe when warmer weather returns my mileage will go back up.

 

<div class='quotetop'>QUOTE(chuck kershner @ Feb 20 2007, 09:29 AM) [snapback]393232[/snapback]</div>

Cold weather and short trips will kill the mileage on any vehicle with an ICE. The only way around it is to have such poor mileage to begin with that you don't notice the drop. If you are only getting 20 mpg and you drop to 16, it doesn't seem like much, but it's a 20% drop. If you're getting 50 and drop to 40, wow, that's a 10 mpg drop! It's still 20%.

Tom

 

<_< So can anybody tell me how the Toyota engineers figured this bladder thing out? What is the purpose of the extra weight? 12 pounds of gas has to be higher than fiting the Prius with a conventional metal tank where all gas could be used. Will my bladder eventually start to sag? (I could make a few comparisons to human bladders, but that's for another discussion :lol: )

 

<div class='quotetop'>QUOTE(Gadgetdad @ Feb 26 2007, 05:05 PM) [snapback]396970[/snapback]</div>

The bladder was not Toyotas idea, it was their solution to comply with EPA. It is only used in the North American Prius, the rest of the world has a regular fuel tank. I seriously doubt that ALL fuel can be utilized in a conventional metal tank.

 

Right on target. I should have read this last week.

I bought my '07 at the end of December '06, and now have 2200 miles on it. I'd been cautious about pushing it beyond the "Add Fuel" warning thus far, but after having never put more than 9 gallons in, I decided to go a bit farther. After all, I had been getting 45 mpg and it was telling me to get gas after 390-400 miles. So the first time I try to push it, I get to 445 miles, and it conks out.

Other than the ~8 warning lights and a couple beeps right when it died, there wasn't much to notice. I was already on my way to the gas station, and it happily went the last 1.5 miles on battery (and still only took about half of the battery to do it). So I get to the gas station, knowing I'm out, and it still only wanted to take 10 gallons. I eventually got it up to 11.6 gallons but it took probably 10 minutes of fiddling, repositioning, click-click-clicking, etc. It didn't spill though. Hopefully the newfound fill level will help stretch the bladder. It's not terribly cold in Atlanta, but this car is so new it has never seen hot weather before.

So from now on I won't push my luck on refilling... but I'll have to look at the fill level with greater skepticism now.

The bladder is in place in the US Prius and in (as far as I know) all other cars sold in the US that meet California's toughest emission standard for gas-powered cars, called AT-PZEV. That emission tier requires (among other things) that the car produce ZERO evaporative emissions while parked. That makes sense for California because gas has a pretty strong tendency to evaporate, and the fumes are 1) toxic and 2) react with other stuff in the atmosphere to cause ozone, fine particles, smog, etc. The bladder is installed inside what is otherwise a fairly normal gas tank and keeps air from coming into contact with the gas. If there's no air space, the gas can't evaporate. Some manufacturers only install the bladders into cars going to states that use the California emission standards; with the Prius Toyota is making them all the same.

The bladders are also in use in at least some Crown Victorias after the scandal over cop cars bursting into flames when getting rear-ended. Ford seems to think it will help prevent fuel leaks when the tank gets pierced in catastrophic impacts.

 

Thank you, I feel relieved knowing my bladder is better.

 

The ongoing "bladder" discussions, as previously mentioned, are a "Prius Regular" insofar as subjects for posts. Many "techniques" have been used to try to get more fuel into the bladder/tank, inclusive of slow pumping 'til the nozzle clicks 'off,' them 'burping' the bladder by removing the nozzle and pumping a little more, repeating the procedure a couple of times, etc. Personally, I have adopted a 'one burp' procedure.

Ambient temperature has its effect [stiffer bladder in colder weather]; the sensitivity of the fuel nozzle 'click off' setting has its effect. Only once in two Prius and approaching 2½ years of Prius driving have I stretched the bladder trying to pump more and more fuel, resulting in a fuel spill - that convinced me to not push so hard to get the last ¼ gallon in the tank.

I have no fascination with bragging that I could 'pump XX.XX gallons.' I usually fuel at one non-blinking pip and do not concern myself with how many gallons I'm able to pump. I do record the data for my ongoing spreadsheet in which I compare the MFD numbers with the 'gallons pumped vs. miles driven' calculations. I find the MFD >98% accurate - "close enough for government work!" Over many fuelings, the spreadsheet becomes more accurate.

 

<div class='quotetop'>QUOTE(Charles Suitt @ Feb 27 2007, 01:16 PM) [snapback]397308[/snapback]</div>

I agree completely.

I really don't get the fascination/obsession people seem to have about "not being able to fill the tank". According to spec, the Canadian Prius holds 45L of fuel. Yet, the most I have been able to pump so far is 36.47L, (more than 2 US gallons short) and that was running on fumes (I have only gone as low as the "blinking pip" twice, and I filled up immediately each time).

Even on my old car (96 Acura Integra) - which supposedly held 45L as well - I was hard pressed to get it over 40L, and I topped off relentlessly with that car. Do I care that I couldn't fill either car "completely"? Not really. What I do care about is that we are getting better fuel efficiency and pollute less than any other 4 or 5 passenger vehicle on the road today. :lol:

My philosophy is simple - when there is 1 or 2 bars left, I go to my favorite gas station and pump 87 octane until it clicks off. Once it does, I just put in a couple cents more to round to the nearest dollar (which doesn't take long in Canada <_< ). Lather, rinse, repeat... just not as often as all other drivers on the road.

 

The US owners manual says "The fuel tank capacity is decreased at low ambient temperature. (decreased by about 5 L (1.3 gal., 1.1 lmp. gal.) at –10 C (14 F).)"

Ken@Japan

 

<div class='quotetop'>QUOTE(ken1784 @ Feb 27 2007, 07:44 PM) [snapback]397537[/snapback]</div>

Yes, that does sound familiar and makes perfect sense, however, my point was that even at "normal ambient temperatures", I doubt anyone will be able to fit as much as fuel into the tank as the specs indicate.

 

<div class='quotetop'>QUOTE(conversion02 @ Feb 19 2007, 07:18 PM) [snapback]393079[/snapback]</div>

The gas gauge is accurate to within + or - 8 gallons.

It is normal, we all have to get used to dealing with it. I advise you to never *guess* how much fuel you have, when it starts asking for fuel, fill it up.

My biggest problem is that I fill up so seldom that I forget to look at the dang fuel gauge. My last car was a supercharged buick. I checked the gas gauge first thing when I got in the car. When I floored it, I could watch the gas gauge move. Quite a difference with the Prius.