Gas From Pump Slowly Goes In, Then It Spills Back Out (Part 2)

Discussion in 'Gen 2 Prius Technical Discussion' started by NoThrowningRocks, Sep 6, 2021.

  1. NoThrowningRocks

    NoThrowningRocks Junior Member

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    A Job Too Big for MacGyver?
    Is it Possible to MacGyver a Workaround to These Requirements? [Dealing with Testing Fuel Tank EVAP Components; Named Refueling Issue; and DTC P0441 & P0455]


    RE: Testing CCV (below)
    : Is this outside the scope of DIY? Is there a work-around to (or substitute for) using an EVAP pressure tester to complete the Canister Closed Value (CCV) test or another way to give strong indication this is source of problem?

    RE: Purge Flow Switching Value (below): Similar question regarding a hand vacuum pump. Can anyone provide reference to where to obtain one or an alternative?

    RE: Intelligent Tester: Also, in several related Repair Manual articles there's reference to "connect the intelligent tester" to the DLC3. Can the intelligent tester do things Techstream cannot? Also, I can research further and report back, but I'd appreciate it if someone could briefly explain the difference between the ODBII and DLC3 ports. (Hope "intelligent tester" doesn't mean someone other than me testing EVAP components or I'm screwed, lol).

    How to Test Bladder-Type Fuel Tank EVAP Components The following tests help identify potential problems with EVAP components. If these tests indicate a faulty component, see the Repair Manual for complete diagnosis and service procedures.

    Testing Canister Closed Valve
    1. Connect an EVAP pressure tester to the EVAP service port.
    2. Set the pump hold switch to OPEN and the vent switch to CLOSE.
    3. Turn the pump ON for 15 seconds, then turn it OFF.
    4. The tester gauge pressure should drop and should not hold pressure.
    5. Use the Techstream active test to turn the canister closed valve ON.
    6. Turn the EVAP pressure tester pump ON again for 15 seconds, then turn it OFF.
    7. The tester gauge pressure should hold pressure.
    8. Use the Techstream to turn the canister closed valve OFF. Pressure in the system should now decrease.
    upload_2021-9-6_22-8-7.png
    Purge Flow Switching Valve (Tank Bypass Valve)
    1. Remove the hose from the EVAP purge VSV and attach a hand vacuum pump to the purge flow switching valve.
    2. Use the Techstream active test to turn the purge flow switching valve ON.
    3. Raise the vehicle.
    4. Clamp the hose from the purge flow switching valve to the vapor pressure sensor and apply vacuum with the hand pump. The purge flow switching valve should hold vacuum.
    5. Use the Techstream active test to turn the purge flow switching valve OFF. Vacuum should be released.

    Fuel Cutoff Valve
    1. Remove the fuel cutoff valve from the fuel filler neck assembly. Keep the valve upright — do not tip it.
    2. The valve should not contain any liquid fuel. If there is fuel in the valve, drain it and confirm there is no fuel in the charcoal canister.
    3. Gently blow light air pressure through both ports on the upright valve. Air should pass through both ports with the valve upright.
    4. Turn the valve upside down and again gently blow through both ports. Air should not pass through either port with the valve upside down.

    Refuel Check Valve
    1. Remove the refuel check valve from the fuel filler neck assembly.
    2. The valve should not contain any liquid fuel. If there is fuel in the valve, drain it and confirm there is no fuel in the charcoal canister.
    3. Gently blow light air pressure through the larger port on the valve. Air should not pass easily through the larger port.
    4. Gently blow light air pressure through the smaller port on the valve. Air should pass easily through the smaller port.
     
    #1 NoThrowningRocks, Sep 6, 2021
    Last edited: Sep 6, 2021
  2. JohnPrius3005

    JohnPrius3005 Member

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    Hi NoThrowingRocks, If you search PriusChat you'll find that a few others have had this same problem. Some have figured out a "non standard", "non approved" work around, which will actually allow them to get fuel into their tanks. I recall some have simply replaced the filler neck until they found one which worked, and others have carefully cut plastic seals which defeats some part of the system but does make the car usable.. From what you've down/up loaded it appears that it takes special equipment to fully test this system and rectify the problem items. I seriously doubt that one in 100 trained Toyota techs know exactly how to do this, or some of the other highly complex procedures on this car. Consequently if you take your car to a "factory authorized and trained service center" you end up paying a high hourly rate for a technician to learn how to do something on your car, or they end up doing something completely different which their experience tells them should work. Maybe it does, maybe it doesn't. But you pay anyway.. And it's extremely difficult to find an experienced, qualified and trained tech who has specialized in the particular issue you might have. So, you're left with a couple of options: you can go through the full procedure in the manuals, getting your hands on the equipment required, or you can search what others have done and do that. Of course in all I've said above I'm using "you/your" to include "me/my". Good luck to you.
     
  3. SFO

    SFO Senior Member

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    The "intelligent tester" is now "techstream", and the data link connector (DLC) is the OBD2 port.

    Here is the workup for DTC P0455 (and P0442 / P0456) : https://share.qclt.com/%E4%B8%B0%E7%94%B0%E6%99%AE%E7%91%9E%E6%96%AF%E5%8E%9F%E5%8E%82%E8%8B%B1%E6%96%87%E6%89%8B%E5%86%8Cpdf%E6%A0%BC%E5%BC%8F/Repair%20Manual/04pruisr/05/2054m/cip0442.pdf

    Here is the workup for DTCs P0441 and P0446 : https://attachments.priuschat.com/attachment-files/2018/04/143457_cip0441.pdf
     
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  4. NoThrowningRocks

    NoThrowningRocks Junior Member

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    Given the huge volume of data obtained from the TIS subscription on this matter, along with some valuable insight from experienced mechanics, I definitely leaning toward a "non standard" work around to get fuel in the tanks unless I can get some tips doing a "by the books" diagnostic. I'm thinking just getting the more simple diagnostics (ensuring no fuel in valves/places it doesn't belong) will be the extent of that work while simultaneously researching other ways of getting gas into the vehicle.

    I also agree, given complexities of the EVAP system, well under 5% of trained Toyota techs know exactly how to correct the problem cost effectively. I'm hoping for some help, but will continue searching for workaround solutions (while trying to pass GA emissions standards for car registration).
     
  5. NoThrowningRocks

    NoThrowningRocks Junior Member

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    Great, many thanks!
     
  6. NoThrowningRocks

    NoThrowningRocks Junior Member

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    I was able to fill the tank (by pulling pump handle 15-20%, so slow fill) until the fuel cap was accidently lost and not replaced for a couple days). Given material read, this appears relevant but not sure of implications or how it may point to direction of correct diagnosis.
     
  7. ChapmanF

    ChapmanF Senior Member

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    Hand vacuum pumps are easy to come by in any auto parts store and not very expensive.

    EVAP pressure testers are another matter. The fuel system can easily be damaged by pressure above a very small limit; these testers are built around very specialized low-pressure regulators that aren't supposed to even fail in a way that could overpressurize the system. And they will generally be used with some inert gas like nitrogen, as pumping a concentration of oxygen into a system filled with fuel vapor verges too close to bomb-making for comfort.

    But even good independent auto repair shops ought to have one. If you call around and ask who has a tech that's good with EVAP / ORVR systems diagnosis ... it's tricky and a bit of a specialty area, but it's not like it's never covered in training for serious techs.

    Yeah, that was the former custom-hardware thingy that they phased out in favor of Techstream on a laptop.
     
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  8. NoThrowningRocks

    NoThrowningRocks Junior Member

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    I was thinking hand vacuum pumps would def be the easier of the two to come by (had no idea of the EVAP pressure tester and proximity to accidental bomb/explosion :eek:...).

    Looks like at least 3-4 major EVAP values as sources of potential problem (Purge Flow Switching Valve, Fuel Cutoff Valve, and Refuel Check Valve) can be checked off the list fairly easily. We'll see how it goes... I may know where one of the better techs in the area may have access to the EVAP pressure tester as well. Thanks again @ChapmanF !
     
    #8 NoThrowningRocks, Sep 7, 2021
    Last edited: Sep 7, 2021
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