Gas From Pump Slowly Goes In, Then It Spills Back Out... (help!)

Discussion in 'Gen 2 Prius Technical Discussion' started by NoThrowningRocks, Aug 9, 2021.

  1. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    15,200
    10,578
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    Have you signed up on TIS yet?

    Probably no real substitute for learning how the evap system works, how it tests itself, and what the outcomes mean....
     
  2. NoThrowningRocks

    NoThrowningRocks Junior Member

    Joined:
    Jun 16, 2019
    73
    17
    0
    Location:
    Atlanta, GA
    Vehicle:
    2006 Prius
    Model:
    II
    Funny you mentioned TIS, I'm signing up later today as I found a neighbor who is mechanically inclined with tools (not sure if I mentioned before, but fire destroyed home and lost everything while continue battling insurance, lender, and loan servicer) and willing to help. He could use Toyota TIS data as well and I'm planning on the two-day subscription, so waited until he's free to use access also (pretty sure TIS smart enough to not allow dual logins, so I need to get Prius data and then he can get his).

    Though it'd be great if the charcoal canister is free from fuel exposure, not holding my breath, and in process of trying to source affordable replacement values as necessary. Neighbor goes to nearby salvage yard for replacement items when feasible. I know this is inconsistent with the practice of employing systematic approach to troubleshooting, which TIS will hopefully address, but bisco stated in related post elsewhere the bladder is commonly problematic with the Gen II.

    Assuming at least one of the purposes of the bladder is to minimize gas vapors (source of fire/explosion), is it safe to assume the gas put into the tank but then pouring (or gushing) back out is related to the bladder? Then again, the bladder could be functioning perfectly, but it's receiving bad data from elsewhere telling it to expand, which is the root of the problem.

    Hey, thanks again for your replies. Like everyone, I have outside stressful things I'm dealing with and having you get back to me - even if with a swift (but gentle) kick in the a$$ to get me focused on the right thing - is deeply appreciated!

    Take care. And hey, if you have *any* finance, investment, valuation or related questions (is my broker ripping me off? what mutual fund makes sense for me? what asset allocation is appropriate? I'm looking to buy/sell my shop, how much is it worth?) PLEASE DM me and I'm more than happy to do whatever I can to return the countless favors you've done for me!
     
  3. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    15,200
    10,578
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    I'm not aware of any commonly-known problem involving the bladder, other than the fact that it is floppier in warm weather and stiffer in cold weather and messes with the minds of people who want all their fillups to look like the exact same size of tank. :)

    The bladder is much simpler than you're thinking, just a dumb, stretchy ... bladder. Nothing tells it to expand or contract. It expands when you pump fuel into it.

    It is there to reduce the escape of fuel vapor into the atmosphere every time you refuel. If you picture an old-skool fuel tank, just before you refuel, you've got a little fuel in the bottom and ten gallons of vapor-laden air. Then when you pump it full of fuel, you've literally forced ten gallons of vapor-laden air out the tank vent and into the outdoors, where it reacts to make low-altitude ozone and smog.

    With the bladder, as you use up the fuel, the bladder just shrinks along with the liquid volume, and there's hardly any vapor there, and of course what's in the tank outside of the bladder is just fresh air.

    The car's self-testing includes checks to make sure that outside-the-bladder air does not contain fuel vapors. A leak in the bladder would be one way for that check to fail, but I think what mr_guy_mann was getting at in #9 was more that fuel overflow into that outside-the-bladder space, such as from a refueling mishap where liquid sloshed down the wrong pipes, would be another way for that check to fail.

    I've never read anything here about the bladders going bad or springing leaks; if it happens at all I think it's quite rare.
     
  4. NoThrowningRocks

    NoThrowningRocks Junior Member

    Joined:
    Jun 16, 2019
    73
    17
    0
    Location:
    Atlanta, GA
    Vehicle:
    2006 Prius
    Model:
    II
    Okay, what you said makes a lot of sense. I'm prone to over-thinking things most of the time.

    This is where I got the idea related to the bladder (which I probably took out of context, so my bad):
    upload_2021-8-17_19-19-59.png

    Of the 3-4 possible items that may need replacement (thinking mostly valves and charcoal canister), are there any you recommend against getting from a salvage yard or going with a non-OEM part?
     
  5. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    15,200
    10,578
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    Yeah, I think that "usually the bladder" is most appropriate for responding to the very common Gen 1 and Gen 2 complaints from people who seem really irked that they can't figure a single consistent tank "size" from all their fillups. When that's the complaint, then "yeah, that's the bladder" is usually the right response.

    To be clearer about it, that applies when people are irked by the normal fact that their fillups might sometimes show 7.3 gallons and sometimes 8.5, 9.1, that kind of thing. (I've never seen what the excitement's about. When my gauge gets to around half I pull into a station, fill until the handle clicks off, pay, and drive away.)

    It is not the response that applies when somebody is failing to get even one or two gallons into the tank, or it is spurting back out. In that situation, something in the ORVR system is b0rked, and ought to be fixed. Then people can go back to being irked about the slightly inconsistent bladder "size".
     
    NoThrowningRocks likes this.
  6. NoThrowningRocks

    NoThrowningRocks Junior Member

    Joined:
    Jun 16, 2019
    73
    17
    0
    Location:
    Atlanta, GA
    Vehicle:
    2006 Prius
    Model:
    II
    Lol, love the last paragraph of your response. I'm in the same camp as you. Tank starts getting low, fill until clicks off, smile at the well under $20 price tag, and happily go on my way for ~2 weeks; Wash, rinse, repeat, no worries.... (except when the gas starts slowly flowing back out, different story). Think it was the slow pouring gas back out that made me imagine a bladder inflating and pushing out the gas. That flawed logic falls apart when I think about how the gas spurts out when it flows into the tank moderately faster (with a 1/5 squeeze of the handle).

    KEY QUESTION:
    I'm going to access TIS in a short while and begin pouring over the information with a focus on getting the car to accept gas and not spit it back out. After going through the first 3-4 steps in the process (mostly confirming fuel isn't where it doesn't belong and emptying it, if appropriate) how would you recommend I test to see if the problem is resolved (or at least marginally fixed)? I may have, at best, 1/4 tank of gas and the closest gas station is about 2 miles away...

    Sorry, now I think about it (long night; family emergency and had to pick daughter up from college and returned about an hour ago) I should buy another gas container, fill it up and see if it accepts it. Not sure how much the tank needs to be put back together, but suppose we'll (neighbor and I) figure it out by trial and error if nothing else. Thanks again.
     
  7. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    15,200
    10,578
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    My best advice would be to start by learning everything you can about how the evap and ORVR systems work in the car, and how Toyota recommends to diagnose them. Once you are signed in to TIS, start with the New Car Features manual ("NCF" tab). That's the conceptual introduction, what the pieces are, what they do, how they do it. From there, move on to the Repair Manual, study the diagnostic steps and monitor tests for the evap and refueling systems. Look up the trouble codes that are related, and the workup steps given for those.

    Before you sign out, look for the 'technical library' tab up at the top of the screen, and find your way to the Toyota technician training course materials. Look for modules on evap and refueling systems. Those will be written in a tutorial way to really bring you up to speed.

    Of course you'll find other modules there on lots of other subjects that might interest you too. But the ones on evap systems are worth reading, because there's more to understanding the systems than a lot of people assume.

    Then here you can post whatever old questions the Toyota docs didn't answer for you, alongside whatever new questions the Toyota docs gave you.
     
  8. mr_guy_mann

    mr_guy_mann Senior Member

    Joined:
    Sep 3, 2020
    1,208
    499
    0
    Location:
    NJ-USA
    Vehicle:
    2006 Prius
    Model:
    Four
    So here's an overview of the gen2 evap system. In order for liquid fuel (red) to enter the tank/ bladder, any vapor (purple) has to leave the bladder and travel to through the canister. More importantly air (blue) around the bladder has to be able to exit through the leak detection valve and filter before venting to the outside. Screenshot_20210814-233118.jpeg prius%20evap.jpeg

    Posted via the PriusChat mobile app.
     
  9. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    15,200
    10,578
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    Yes, I think that does look equivalent to the diagram in the post linked from #2 in this thread, which I think came from one the technician training course modules on TIS.

    [​IMG]
     
    NoThrowningRocks likes this.
  10. mr_guy_mann

    mr_guy_mann Senior Member

    Joined:
    Sep 3, 2020
    1,208
    499
    0
    Location:
    NJ-USA
    Vehicle:
    2006 Prius
    Model:
    Four
    This type of fault is one where it is really nice if you have the correct tools. If I had this car, I would connect my smoke machine (which has a regulated output of 1/2 psi - 14" H2O) to the filler neck and watch the flow gauge. Then start disconnecting things where I can reach them until then flow goes high. If I had to then I would drop the tank and keep at it until I located the restriction.

    I can't think of any decent way to DIY this type of diagnosis. Too much pressure can damage some components.

    Posted via the PriusChat mobile app.
     
    NoThrowningRocks likes this.
  11. NoThrowningRocks

    NoThrowningRocks Junior Member

    Joined:
    Jun 16, 2019
    73
    17
    0
    Location:
    Atlanta, GA
    Vehicle:
    2006 Prius
    Model:
    II
    Thanks guys, I really appreciate your thoughtful responses - extremely helpful! My daughter (starting senior year in college) is having a manic episode, which is a soul-crushing experience as a parent that makes almost every aspect of life challenging. Your guidance is appreciated more than words can express. Tomorrow (today) I should get a chance to dive into this and, thanks to your help, I believe I have a shot at getting this back up running. Thank you again and hopefully my next post will include intelligent, thoughtful questions. Best, John
     
  12. NoThrowningRocks

    NoThrowningRocks Junior Member

    Joined:
    Jun 16, 2019
    73
    17
    0
    Location:
    Atlanta, GA
    Vehicle:
    2006 Prius
    Model:
    II
    I'm into TIS. Where do I find step by step instructions on locating the carbon cannister, for example, and assessing if it is damaged or not? Similar to what was provided on previous page for fuel control valve (?) etc.?
     
  13. NoThrowningRocks

    NoThrowningRocks Junior Member

    Joined:
    Jun 16, 2019
    73
    17
    0
    Location:
    Atlanta, GA
    Vehicle:
    2006 Prius
    Model:
    II
    I'm in the Tech Manual, Engine Control Systems II and Chapter 7 has the EVAP System Diagnosis materials.
     
  14. NoThrowningRocks

    NoThrowningRocks Junior Member

    Joined:
    Jun 16, 2019
    73
    17
    0
    Location:
    Atlanta, GA
    Vehicle:
    2006 Prius
    Model:
    II
    Any recommendations where on site to go to find quickest way to take DTC codes and get info on how to diagnose/fix?
     
  15. NoThrowningRocks

    NoThrowningRocks Junior Member

    Joined:
    Jun 16, 2019
    73
    17
    0
    Location:
    Atlanta, GA
    Vehicle:
    2006 Prius
    Model:
    II
    Does the 2006 Prius have a Closed Tank, Late Type or Early Type EVAP System? (Please don't say all the above, lol)
     
  16. NoThrowningRocks

    NoThrowningRocks Junior Member

    Joined:
    Jun 16, 2019
    73
    17
    0
    Location:
    Atlanta, GA
    Vehicle:
    2006 Prius
    Model:
    II
    Located New Car Features (NCF) Tab and found additional useful info on Evap
     
  17. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    15,200
    10,578
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    (y) sounds like you're looking all the right places.
     
  18. NoThrowningRocks

    NoThrowningRocks Junior Member

    Joined:
    Jun 16, 2019
    73
    17
    0
    Location:
    Atlanta, GA
    Vehicle:
    2006 Prius
    Model:
    II
    Thanks, Found the NCF tab (esp. re Fuel Evap) and the Prius Repair Manual, so pretty much gathered everything on EVAP & ORVR, including the conceptual aspects of the system that's likely relevant. As you mentioned, not light reading but very comprehensive.

    Gathering the process for troubleshooting my current DTCs, which is going well.

    Only thing I haven't found yet is materials that look like below. Any pointers? It similar to what I've seen in the Repair Manual, but not the same...

    2021-08-30_17-56-44.jpg
     
  19. NoThrowningRocks

    NoThrowningRocks Junior Member

    Joined:
    Jun 16, 2019
    73
    17
    0
    Location:
    Atlanta, GA
    Vehicle:
    2006 Prius
    Model:
    II
    Also, is it correct to focus on information in the Engine Control System, Emission Control/Advanced Emissions, and Fuel Tank TIS sections for this specific problem with refueling? Just to cast a wider keyword search net, in addition to "evap" and "orvr" I've used "bladder," "tank," and "canister" and it appears most paths (that appear relevant) generally lead back to those three sections.
     
  20. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    15,200
    10,578
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    I am pretty sure that I snarfed those from one of the tech training courses on TIS, but I am not sure my notes will say which one. Sorry....
     
Loading...