Fuel capacity: 13.6 gallons!

Three possibilities:

1) He has a euro-spec tank, with no bladder. Unlikely.

2) Tank was overfilled, and excess went back into gas station's tank. This can happen, according to some web articles warning against overfilling or topping off.

3) Tank was overfilled, and gas went into carbon vapor canister thing in Prius.

Liquid gasoline is not compressible, so we should assume 13 gallons cannot fit into the US-spec 2004 Prius tank. This IS a 2004, right?

 

yep it's a 2004

 

oh and jfschultz, it's the station at Poplar and Forest Hill Irene... pump #2.

 

I'm too lazy to dredge up the old message I posted in one of the Yahoo fora, but (as I recall) I was able to pump 12.3 gallons into my 2004 Prius in the dead of winter. i.e. bladder contraction season. This surprised me enough that I called the local weights and measures folks. They tested the pump within two days, and the pump checked out as accurate.

Just another data point....

 

To be serious could the bag be torn or defective and not "filling the dead space" ? Could the on board diagnostics find this out? Most cars have a canaster to trap some fumes etc that can be saturated with gas. Is this the case with the Prius? I don't think that these canasters could hold anything like a gallon though much less the amount we are talking about.
Very strange. There has to be some explination.

 

Check here: http://www.priuschat.com/forums/viewtopic.php?t=2314 half-way down the thread for a cutaway view of the 04 tank vs. the 03 tank.

I partially agree with autoxic - #1 - for some reason the car doesn't have a bladder. Chartquist, it may sound like a stupid question, but is there a rubber seal around the opening to your tank? As for #2 (back into the gas tanks), this is the most likely case - that is, if there is a vapor-recovery system on the pumps you used. If there is, you should see little holes around the tip of the nozzle end of the gas pump. I do highly doubt, however, that #3 occured, as there is no straight-line shot to the charcoal cannister, plus I doubt it could hold close to 2 gallons. Next time you fill up, fill up by hand, and if the pump does have the vapor recovery system, place the nozzle into the gas tank opening such that the holes on the tip are outside of the car. If you're still able to get over 11.9 gallons this way, and there is a bladder in your tank, I have no clue what it could be.

Hope this helps!

-m.

 

Just because Toyota says the capacity is 11.9 gallons does not mean that the capacity is 11.9 gallons. I think that many owners here suffer from a faulty tank that does not allow the bladder to fully fill or perhaps fully empty. My tank holds more than 12 gallons or else I have filled up alot of plumbing in the past. Who at Toyota decides how the capacity is rated. I think there is room for interpretation there. In this more than any other part of the car.....YMMV.

 

rflagg... yep, I have the rubber seal around the opening, and I have always noticed that it works very well (to the point that sometimes I have to kinda yank on it to disengage). I never considered that some of the gas could have reversed its way through the pump... wouldn't modern pumps have one-way valves?

 

i think the only real way to verify this capacity is to continue to drive the vehicle and see if you consistantly get to add that much.

I would never take one fillup for granted no matter what.

if you can do it 2 or 3 times in a row, then that would be news.

 

I agree Ray - especially with this gauge, no one can tell what the real capacity is. I was just saying that I highly doubt that the charcoal cannister would be holding 2 gallons, or that there's a tear in his bladder, etc.

I would assume that Toyota, in rating the tank as 11.9 gals leaves room for play (especially with a bladder in there!) Meaning, you getting 12.4 and 12.1 gallons is possible and very well could be your bladder is 'better stretched'. 1.7 gallons over the 'capacity' though seems quite a bit - but I'm still not saying it isn't possible. My real question, and all of our real questions are of course - what is the 'true' capacity of the tank, and what is our best way to deal with the gauge? With this car, perhaps because of the bladder, perhaps because of a software glitch, it seems it varies person to person - some can't get more than 7 or 8 gallons in, I'm averaging no less than 10 gallons but never more than 11.5 gallons, and you're able to get over 11.9. It's just a truly perplexing question when all the variables are considered, from vapor-recovery to splashback to pump calibrations, etc.

I think it all boils down to your last comment - YMMV!

-m.

 

any flexible container has the chance of being stretched. so sure its possible since the bladder would expand into a metal container. the metal container capacity would obviously be larger than the bladder since it also has other items in it besides the bladder.

i couldnt help but notice that in my literature for my 87 Corolla and Ford Pickup both gas tank capacities state approx. in the specs

so perhaps the tank size is only a guideline. that could partially explain why there is a rather large disparity in tank sizes and fillup amounts among the members here.

 

I am still not convinced that the pump is accurate. Several years ago, one of the local TV channels consumer affairs advocate/reporter exposed a gas station owner who rigged his pumps to start cheating in his favor only after five gallons have been pumped. That way he always passed the Weights and Measures inspection and he still stole from his customers.

 

What is the stated capacity of the Euro/Asian versions of the Prius?

 

accordiing to the newscast about inaccurate pumps in WA st, new pumps are nearly impossible to alter after calibration because of time stamping by the software that runs the programs.

apparently nothing can access the time stamping so if the time stamp doesnt match up with the sticker and the records of the state, then the pump has been tampered with.

but in the state study, inaccruracies didnt have so much to do with the meter at the pump but the valve that controlled the flow of gasoline wearing out and becoming inaccurate. it was also found out that the inaccuracy generally ran 2-1 in favor of the gas station owner.

i;ll be honest with ya, i can believe that the tank is bigger than normal. i seem to remember in the past similiar stories with other cars getting more capacity than is normal. its just that Toyota's quality control is so tight and good that having a varience like that is unusual. to be honest with ya, if it would have been a Ford or Chevy, i wouldnt have given it another thought. but the fact that it is a Toyota is somewhat surprising.

there is a story going around in a quality control class i took while working at intel that goes on the line of when Toyota decided to finally build an american assembly plant, they immediately started to interview for parts suppliers to support the plant.

they would call in a prospective supplier and supply them with a blueprint of the part they wanted and ask

"Can you do this for us?"

the supplier before they even looked at it, would say "yes of course we can!"

but a week later the supplier would call back saying there was information missing from the blueprints.
when asked what was missing, the supplier replied that there were no tolerances for the measurements.

well the Japanese didnt know what tolerance meant since there was no comparable word in the japanese language. then the supplier explained that the tolerance was the allowed range of measurement for a given parameter.

the response from the japanese was

"so you want to know how much mistake you can make in the part?"

they supplier replied "no, its not a mistake, its tolerance, tolerance is standard measurement in american manufacturing process."

the japanese replied. "oh we understand. but we are manufacturing a japanese car, not an american car. if you cannot manufacture the part without mistakes, we will get someone who will!"

 

liquids may expand due to temp differences but i dare say that that difference in volume will be minimal. the principle of fluid dynamics dictates that most IF they expand, do so only slightly. if they did expand like 10% as is suggested here, then hydralics would be in for a major hurting.

 

I looked up the volumetric coefficient of expansion for petrol. It's about 0.001/°C, or in other words, about 1% for every 10°C change in temperature. You're not likely to see an expansion/contraction anywhere near ±10% in the same tank!

(For the non-metric people, 10°C is 18°F.)

 

yes but i think its possible that fuel can actually be added in addition to what goes in the bladder in an overflow situation.

from the picture(realize its a schematic so spatial relationships mean nothing.) that was posted on another thread, for the bladder to expand and contract there has to be vented airspace inside the tank that the bladder expands into since the bladder itself should never have any air in it. therefore, its possible that fuel overflowed into the tank outside the bladder.

i dont know what the bladder is made of but im fairly certain the "blowing up a balloon" scenario doesnt apply here. so these hypothetical posts of trying to stretch the bladder are probably groundless.

the only real conclusion IF you can continue to put that much gas into it is that the bladder is simply bigger than average. or leaking.

you mentioned that the gas mileage also took a hit on the fill up which makes think that the gas might be going elsewhere besides where its supposed to be going.

 

UPDATE!

I have now finished the tank... with a good story too! I decided to run it close to empty (and go to another station) to again test the fuel capacity. At 40.5 miles past one fuel bar flashing, I got the out of fuel warnings. If possible, I will take a picture of the MFD before I refill and post it here. I know lots of folks want to know what happens when this infamous event takes place... You get a loud beep accomplanied by a large illuminated red triangle with an exclamation point in it, located to the right of the speedo and to the left of the "maintanance required" idiot light. Also, a red engine logo appears in the upper left hand corner of the MFD.

Since I ran it dry, I have some good tank details (as indicated by the MFD) for this ongoing experiment...

Miles driven: 625
Avg MPG: 48.0
Miles driven with one bar flashing: 40.5

The ambient temps for this tank have been in the low to mid 90s.

Doing the math according to the MFD reveals that for this tank, I burned 13.02 gallons, verifying that the tank capacity indeed exceeds the 11.9 gallons!

Incidentally, I ran out of gas on a hill, close to home. When I went out to check the numbers to write this post, the engine fired in the normal start-up procedure. I didn't plan on running the tank dry (I have gone way past 40.5 miles after one bar flashes), but this ended up being a great experiment nevertheless.