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2008 Drain bad fuel from the tank

Discussion in 'Gen 2 Prius Technical Discussion' started by JohnStef, Aug 16, 2018.

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  1. JohnStef

    JohnStef Member

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    Recently purchased a 2008 Prius with a full tank of gas, the engine runs pretty smooth but has a noticeable tapping sound under light to heavy load. But it goes away under a no load condition.

    I would like to remove the fuel line from the fuel rail and pump the gas out and replace with fresh. I need some guidance on how to energize the fuel pump.
     
    #1 JohnStef, Aug 16, 2018
  2. JC91006

    JC91006 Senior Member

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    I suspect that car burns a lot of oil and it's not related to your gas
     
    #2 JC91006, Aug 16, 2018
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  3. ericbecky

    ericbecky Hybrid Battery Hero

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    I've answered this question not too long ago.
    Not sure the best way for you to search for it.

    Basically I identified where to apply 12v to the fuel pump under the back seat.

    I remember mentioning also that the cover lid was very sharp. Easy to cut yourself.
     
    #3 ericbecky, Aug 16, 2018
  4. ericbecky

    ericbecky Hybrid Battery Hero

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    #4 ericbecky, Aug 16, 2018
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  5. edthefox5

    edthefox5 Senior Member

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    If it’s got close to 200000 miles it’s probably a blown bottom end on the motor, many many posters here have ruined there engines running it low or out of oil. Damage stArts as loud tap which is piston bearing and if continued to drive turns into loud knock. Hilarity ensues when piston #2 makes hasty exit out the side of the block.

    Cause Bad gas=engine no workee much less tappy
     
    #5 edthefox5, Aug 16, 2018
  6. JohnStef

    JohnStef Member

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    Your way removes the rear seat, pulls the fuel pump cover and applies power to the pump, No way to apply power thru a relay?
    One idea I had was to pull the main relay block and pierce the correct wire with 12v, but I don't know which one this is and if this current will go elsewhere and blow something.
     

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    #6 JohnStef, Aug 16, 2018
    Last edited: Aug 16, 2018
  7. ericbecky

    ericbecky Hybrid Battery Hero

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    Removing the lower portion of the rear seat is so simple you don't need tools. Simply pull upwards.

    And from there it is a very short time to unbolt lid
    and apply power.
     
    #7 ericbecky, Aug 16, 2018
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  8. JohnStef

    JohnStef Member

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    Thank you Eric, I should have done this a week ago!
     
    #8 JohnStef, Aug 16, 2018
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  9. ericbecky

    ericbecky Hybrid Battery Hero

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    And once again I'll say that the lid is very sharp! As in razor sharp. Why so sharp? I have no idea.

    Every time I tell myself, "I don't need gloves THIS time. I'm sure I'll be careful enough THIS time and not get cut."

    WRONG!

    Then I just have to grab some extra towels so I don't bleed all over the customer's car.

    :)
     
    #9 ericbecky, Aug 17, 2018
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  10. JohnStef

    JohnStef Member

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    Finally got back to the Fuel Pump
    Eric do I have this right?
     

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    #10 JohnStef, Aug 22, 2018
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  11. fotomoto

    fotomoto Senior Member

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    Then why not add some quality fuel conditioner/treatment and use up the tank? A noticeable tapping sound is usually from a mechanical source (valves typically).
     
    #11 fotomoto, Aug 22, 2018
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  12. JohnStef

    JohnStef Member

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    Eric I just deciphered an electrical diagram for the Prius Gen 2 and the picture I have is correct, happy. Now I will proceed.
     

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    #12 JohnStef, Aug 22, 2018
  13. JohnStef

    JohnStef Member

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    I put 2 cans of SeaFoam in already, I don't know what effect this has on Octane though.
     
    #13 JohnStef, Aug 22, 2018
  14. ericbecky

    ericbecky Hybrid Battery Hero

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    I can't seem to get the photo.
    Does it match up with my kinda lame description?
     
    #14 ericbecky, Aug 22, 2018
  15. fotomoto

    fotomoto Senior Member

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    I think you way over medicated with 2 cans (see directions) but if boosting octane to reduce ping is your goal, there are additives for that at auto parts stores.
     
    #15 fotomoto, Aug 22, 2018
  16. Dxta

    Dxta Senior Member

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    How did you conclude the issues you had was related to fuel system?
     
    #16 Dxta, Aug 23, 2018
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  17. JohnStef

    JohnStef Member

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    Yes it does Eric, you callout in the
    Diesel container & the smell test thread noted above:
    There are 2 rows of 4 pins.

    I'll arbitrarily call the position on the far left "1", position on far right "4"
    Power can be applied to the pins in row "3".
    For those 2 pins, apply positive to the pin in the row nearer the connector tab, negative to the pin in the row farther from the tab.

    So my data comes from Toyota and they. yours and theirs, both agree. I will apply a tired 12v LiPo battery tonight, under load it will drop to 11.2v, if I see fuel flow, then i will know I have it right and then apply a 12.6V portable lead acid battery. This is a little more complex than needed, but I have these things in my garage and I don't want to destroy stuff, I'm in "caution" mode.
     
    #17 JohnStef, Aug 23, 2018
  18. JohnStef

    JohnStef Member

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    trial and error
    The car ran rough intermittently and the tap tap tap sound was louder than it is now. My 1st thought was sticky lifter. The Prius mechanic I consulted said, No, 9 times out of 10 it is bad combustion. It had 2 bad coils, they had black soot on them and one of them threw a coil pack code. I replaced them with used parts, I have no codes related to bad coil packs. So I am running down every method to improve combustion, my last stop is the old gas replacement.
     
    #18 JohnStef, Aug 23, 2018
  19. edthefox5

    edthefox5 Senior Member

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    Car has solid Lifters.
     
    #19 edthefox5, Aug 24, 2018
  20. JohnStef

    JohnStef Member

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    Ed what does this mean?
     
    #20 JohnStef, Aug 24, 2018
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