Third-generation Prius resolves bladder issue

When the next-generation Toyota Prius hits dealer showrooms in late May, it will come with a bigger engine, improved fuel economy and solar-powered cabin cooling.

What it won’t have is the innovative "fuel bladder" that has served as the gas tank for the Japanese-built hybrid.

Toyota decided to ditch the bladder in part because some Prius owners complained that it held less fuel than the 11.9-gallon capacity claimed in the car’s owners manual — potentially taking a big bite out of the car’s range between fill-ups.

The new 2010 Prius — the third-generation of the groundbreaking gas-electric hybrid — will use a rigid tank made of a lightweight resin rather than the collapsible bladder.

"The chief reason was because one of the sore points with the current-generation Prius was the ability to fill up the fuel tank and the accuracy of the fuel gauge," said Bill Kwong, a spokesman for the automaker.

The change is coming too late for Darlene Sharar, an engineering technician who lives in rural Washington and often drives in areas where gas stations are few are far between.

"In any other car I’ve owned, I know a tank of gas will get me 'X' number of miles," Sharar said, adding that she often could pump no more than seven gallons of gas into her 2008 Prius even when the fuel gauge was flashing "empty."

"Instead of a range of 500 miles, I’ve got a range of 300 miles," she said. (The Prius gets 46 miles per gallon in combined city-highway driving, according to government figures.)

Attempts to get Toyota to fix the problem were unsuccessful, she said. In an e-mail to Sharar, a Toyota customer service representative said the issue involves "the design of the fuel tank and there is no repair available to change the design."

Sharar eventually traded the Prius in on a new 2009 Toyota Camry.

The automaker blames the problem in part on temperature changes. The Prius owners manual notes that the capacity of the fuel bladder drops by about 1.3 gallons at 14 degrees Fahrenheit. Maintenance manuals, meanwhile, note that the problem often can be solved by recalibrating the fuel gauge.

Kwong said that owners complaining of a bladder problem usually say the tank won’t take more than 9 1/2 or 10 gallons of fuel.

"I’ve never heard of only being able to get seven gallons" into the bladder, as Sharar contends, Kwong said.

Over the years, the National Highway Traffic Safety Administration has gotten a dozen or so complaints from consumers about the Prius’ fuel-tank capacity or the accuracy of its gas gauge, which can be a related issue. The agency hasn’t formally investigated the complaints.

Fuel bladders, common in airplanes and racing vehicles, are a rarity in commercial passenger cars, which typically use rigid tanks made of high-density plastic, said Craig Hoff, a professor of mechanical engineering at Kettering University in Flint, Mich. By collapsing as fuel is pumped to the engine, bladders help prevent fuel vapor from building up in the tank, thereby reducing hydrocarbon emissions.

The Prius’ new fuel tank will use an improved vapor-recovery system that will allow the car to retain its low-emissions rating from California regulators, Kwong said.

—Martin Zimmerman

Photo: Toyota Motor Corp.

Comments

[EB]

I have a 2005 Prius and I have NEVER been able to put more than 8.5 gallons in it....even when the tank is flashing Empty. I have never heard of a Prius owner actually putting 10 gallons in their supposed 11.9 gallon fuel bladder. It is a very common problem that Toyota only reluctantly admits. I am shocked at how they downplay the issue.

[travis]

I have a 06 prius, and I've found that the gauge either shows near full or near empty, nothing in-between. I haven't had as much of a problem with filling, I usually can just put 10 gallons in, but that's understandable since most gauges show you're empty when you still have a gallon in the tank just so you don't completely run out.

[david]

How are Prius Owners certain
the bladder is empty, perhaps
a fuel reserve exists? I would
like to hear from some owner
who has a Prius that has RUN OUT of Hydrocarbon fuel.
Let's look at his fuel ticket?

Beneficial owner of TM shares
and owner of 2 Camry's. Previously Cresida, previously Datsun Maxima & 280Z. Houston TX DBS.

[karen]

Agreed that the tanks are pretty small. It doesn't cost much to fill the tank of my 2005, but the tank doesn't hold much, either. Other Prius owners told me never to let the tank get below three bars because it could be dangerously close to empty, even if the fuel gauge doesn't indicate that.

Not a good situation to be in if you travel around a lot for work.

[Dave]

My 09 ran out of gas at 438mi - computer indicated about 44MPG avg. when I filled up, it would take not a drop over 10.5G!

[maureen]

My 08 Prius ran out of gas today. Iit said I was getting 43 mpg average and I had exactly 430 miles on that tank of gas. And funny, but I was only able to put 10 gallons of gas into the tank.

Thank goodness for the hybrid system. I made it to the gas station on electric power.

I love Toyotas and I own TM stock but this is a problem that should be fixed.

[JIm Young]

My 09 also ran out of gas. I had looked at the fuel gauge not long before it ran out and it said there were 3 bars of fuel available. When I filled, it took about 10.3 gallons (should take 11.8 gallons)

The battery saved us. We were able to use it to go about 2 miles to a farm house to get a gallon of gas.

[Portia Danielson]

I have a 2006 Prius and have complained about the "bladder" problem from the very beginning with no interest at all from my dealership in resolving it. Since I try my best to get it "full" (I live in Fargo, ND and don't enjoy trying to fill it up for 15 minutes in the -20 degree temps) I seem to always have an "overflow" problem as well with a lot of gas gushing/shooting out all over me and the car. No more Prius's for me!!