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Fuel Bladder Necessary for PZEV Certification? Apparently Not.

Discussion in 'Gen 2 Prius Technical Discussion' started by Rokeby, Jul 25, 2008.

  1. Rokeby

    Rokeby Member

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    The car next to me in the parking garage today had a PZEV sticker on the
    driver's side rear window, just like my Prius. I stepped 'round to the rear to
    check the make, and it was a Camry.,,. A CAMRY!? (This leads to the
    suspicion that other Toyota models are similarly qualified,) "Strange," thinks
    I, but then my eye fell on the license plate... you guessed it, California.

    [Edit] PZEV; Partial Zero Emissions Vehicle.

    So far -- knock wood -- I haven't run out of gas, nor had the dreaded BURP!
    when refueling. I fill up at 2 pips. Occasionally when fueling, I stop the pump
    and push the nozzle in really hard, and rotate it on the theory that it will
    release any built-up pressure. Hey! Don't laugh, when you don't understand
    the science, ritualistic behavior is a good fall-back.

    From other investigations, I know that the Ford Focus and various Subaru
    models sold in CA also carry the sticker.

    So, there it is, the fuel tank bladder is not necessary to meet PZEV
    requirements.

    Just why is it then that Prius owners are saddled with this millstone?
    What is it really doing for us, and for the environment?

    N.B. For new readers/owners, to get the low down on the complexity of the
    bladder and associated systems go here:

    http://www.autoshop101.com/forms/Hybrid13.pdf

    For a full sense of the frustration and aggravation it can cause, use the
    search function with "bladder," "guess gauge," and "ran out of gas" as the
    search terms.
     
  2. thepolarcrew

    thepolarcrew Senior Member

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    I wonder if it wasn't a trade off for safety reason and proximity to battery?

    Don't feel bad about the handle thing, just tell any one you seen me do it too!
     
  3. john1701a

    john1701a Prius Guru

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    Think about a future where a hybrid uses waste bio-matter ethanol as fuel. With the engine frequently off, evaporative emissions from that are even more difficult to deal with than with gas... unless it has a bladder.

    .
     
  4. morpheusx

    morpheusx Professor Chaos

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    I was thinking that in theory the bladder makes it possible to get Slightly better gas mileage since the vapors can't escape. But I don't understand the science of it either and many of our friends in Europe, Asia, and Australia who don't have it report about the same results or better in terms of consumption.
     
  5. diamondlarry

    diamondlarry EPA MPG #'s killer

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    I think this pretty much confirms my suspicion that Toyota just plain dropped the ball when it comes to the bladder. Since the bladder isn't necessary for emissions ratings it just seems that more problems were created by the addition of the bladder such as the wildly fluctuating accuracy of the "guess gauge" and the fuel burping problem. The fuel burping alone probably cancels out or even exceeds the emissions that they hoped to save.
     
  6. ranchogirl

    ranchogirl New Member

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    I saw a Ford Focus today with a FZEV sticker on the side window. I have a lot to learn about what this means, apparently.
     
  7. thepolarcrew

    thepolarcrew Senior Member

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    Some one had said some thing about ethanol. Haven't checked the specs of total fuel system, but is the fuel line stainless.

    If yes, would be flex ready and could be sold into South America as is or a few mods.

    If no could also be forward looking to that MKT as well as US. Simple change out and away you go in a time of limited oil.

    My dad was a MECH, he was always PO that us car makers were going wrong direction when it came to compression. (US went to low) His threory was high comp and ethonal or methanol ect.

    Where as this vehicle has 13 to 1 comp. Would burn either very good, in theory!
     
  8. JamesWyatt

    JamesWyatt Señior Member

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    I got an 11.05 gallon fill-up the time before last which allowed 530 miles on a tank where I only got 47.5 mpg. And I had just gone down to one pip. Heck, I went 230 miles before the first pip went. I hate that I don't have a larger and more consistent gas tank. But, it's not the end of the world.
     
  9. thepolarcrew

    thepolarcrew Senior Member

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    Have had a couple 11+ on 1 pip. I hear Ya!
     
  10. diamondlarry

    diamondlarry EPA MPG #'s killer

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    I have had 3 fill-ups of over 12 gallons. The last one was 12.4 gallons on a flashing pip that went from mile 892 to mile 1052 on the MFD at which time I chickened out and went to the station; still under engine power I might add.
     
  11. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Well, there is a difference between a PZEV vehicle and an AT-PZEV vehicle: Partial zero-emissions vehicle - Wikipedia, the free encyclopedia

    Prius falls into the latter category. Camry Hybrid also is AT-PZEV certified: Toyota Camry Performance & Specs

    The fuel tank bladder is intended to reduce hydrocarbon emissions into the atmosphere. The good news is that the Camry Hybrid fuel tank does not have a bladder. However instead of a bladder, the fuel tank has an extra pump that is intended to help keep gasoline vapor out of the air - hence, it also contains a layer of complexity that regular vehicles do not have. Highlander Hybrid has a similar fuel system as Camry Hybrid, although HiHy is PZEV certified.

    My guess is that 3G Prius will likely have a similar fuel system as CamHy and HiHy since the 2G fuel system is not as easy to use as we owners would like.

    Why does Classic and 2G Prius have the bladder while other Toyota hybrids don't? Probably because the US Prius fuel system was designed back in the late 90s. Toyota had a chance to learn from that and designed an all-new HiHy fuel tank system first introduced in 2005.
     
  12. ranchogirl

    ranchogirl New Member

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  13. Rokeby

    Rokeby Member

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    Having to put up with the vagaries of the fuel tank bladder irks me to no end.

    Up until I discovered that other far less sophisticated cars than the Prius
    have the PZEV rating, I accepted the quirkiness of the whole fuel
    bladder/"guess gauge" thing as a necessary part of "doing the right thing"
    vis-a-vis ecological responsibility. But now that I know that countless
    models of Fords, Hondas, Subarus, Toyotas, and God only knows what else
    have the same rating and no fuel tank bladders, I'm on a slow burn.

    I really appreciate the info posters have provided. But something Patrick
    Wong said just makes me steam:

    "Why does Classic and 2G Prius have the bladder while other Toyota hybrids
    don't? Probably because the US Prius fuel system was designed back in the
    late 90s. Toyota had a chance to learn from that and designed an all-new
    HiHy fuel tank system first introduced in 2005
    ." [emphasis added]

    What? Toyota had a better answer prior to 2005, and put it in the HiHy, and
    not in its flagship hybrid the Prius?

    Just how is that realization supposed to make me and all the other 2006,7,8
    "Gen2.5" owners happy?
     
  14. bwilson4web

    bwilson4web BMW i3 and Model 3

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    My first computer used amplifiers, resistors, and capacitors. Next to it was a computer that used a TTY terminal with punched paper tape. Then came the 80-column cards and readers followed by all manner of dumb terminals or coax connected displays. Today, I use a laptop and program whatever and whenever including small computers the size of a cracker crumb.

    Technology changes and sometimes we have to put up with systems that taught us "lessons learned" so the next versions are better than those before. Often the newer systems cost less and work better than the ones that came before. It is how the world of technology works.

    So maybe in 2010 we'll see the end of the bladder tank or maybe not. Regardless, it is unlikely we'll see it in any new designs and we can be thankful for that.

    Bob Wilson
     
  15. Rokeby

    Rokeby Member

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    Bob,

    I'm in a peckish mood tonight, so I'm going to play devil's advocate. I mean
    nothing personal here, it's more a rant aganist Mother Toyota.

    It may be some element of perversity in my point of view tonight, but it
    seems like what you've said supports my sense of simmering frustration.

    It would appear that Toyota had the "newer system" in '05, but chose not to
    implement it in the Prius in '06. Could it be that they were resting on their
    corporate laurels, and in an market with no true competition, simply left
    "good enough" alone? If so, there's no leadership there. Or could it be that
    implementing a new system would have been seen as an acknowledgement
    of the inherent weakness of the bladder and engendered backlash amongst
    2003, 4, and 5 model buyers stuck holding the bag, as it were? Keeping the
    fuel tank bladder was then purely a matter of "saving face."

    I wonder if there are any other surprises in the way of technological
    advances withheld.
     
  16. miscrms

    miscrms Plug Envious Member

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    If the bladder is the price to pay for all the other pluses in a Prius, I'd say we're still way ahead of the game. I honestly can't fathom why people get so worked up about it.

    Every vehicle on the road is a compromise of technology, performance, and cost amongst other things. When the Prius system was developed it was already on the cutting edge of emissions technology. New technology costs money, making it tough to roll it out in a moderately priced vehicle. You'll notice, for example, that all of the Lexus hybrids and Camry Hybrid also have lower tailpipe emissions than the Prius. I think this is simply a combination of newer design, and the ability to pack more high tech goodies into a vehicle at a higher price point. The '06 "redesign" of the Prius was exceedingly minor. Aside from the MFD, taillights, the touring suspension, and a few other cosmetic things they are basically the same car. Making any more systematic changes would have required a huge amount of testing and certifications that would have greatly increased the cost of the changes. My guess is that at that time, based on the number of sales to that point Toyota would have been doing well to have broken even on their huge initial investment in the Prius and was not up for pouring a bunch more money into it until it had proven itself financially successful. I can't really blame them for that. They had already been waiting about 8 years to see their investment and patience pay off. Now that the Prius is a clear success and we know a major revision is coming next year I would fully expect Toyota has put everything they've learned in the last 10 years into it, assuming it fits within the Prius' price point.

    Rob
     
  17. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Most car companies including Toyota will produce a given model for a six-year period (i.e., 2G Prius will be produced from the 2004 to 2009 model years). During that period, it would be unusual to see substantial engineering changes made to the model, especially when annual sales in the US are only 150K-175K units per year. This allows parts suppliers to amortize tooling over a longer production run and reduces parts costs, field support costs, etc.

    You may or may not be happy with the result. However, it is what it is. Hopefully 3G will have a fuel system similar to CamHy and HiHy.
     
  18. john1701a

    john1701a Prius Guru

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    Yup, mid-cycle updates are definitely not the norm. That's why the introductions of the Highlander and Camry hybrids were so exciting. They're sneak previews of what continuous engineering improvements bring. Not all changes trickle down to the lowest priced offerings. But in our case, expecting things like the much smaller inverter is quite realistic.

    .
     
  19. Rokeby

    Rokeby Member

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    Well, it's a new day, I got a good night's sleep and have had a cup of strong
    coffee. I don't feel so put upon by the seeming arbitrariness of the the fuel
    system. I'd like to thank the responders for the reasonableness of their
    posts.

    I can now look at the fuel system from a much broader perspective including
    production cycles, vehicle pricing, and Toyota's recovering its long term
    investment in bringing the Prius to market.

    In this quieter, more sanguine mindset, I was able to go back and look at the
    fuel system diagrams, and see them afresh. It it remarkable how the
    system accommodates the many possibilities for things going awry in the
    real world.

    Nonetheless, at times it is hard not to think that the fuel system was
    designed using a map of the New York subway system as a template.

    http://www.autoshop101.com/forms/Hybrid13.pdf
     
  20. Patrick Wong

    Patrick Wong DIY Enthusiast

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    My guess is that the US Classic and 2G fuel system was designed by a bunch of newly-minted engineers who graduated from the Rube Goldberg school of engineering! :D
    Rube Goldberg machine - Wikipedia, the free encyclopedia

    The CamHy and HiHy fuel systems are more complex than normal; however I haven't seen any complaint about owners having trouble refueling or a pump failure, so far.