2011 silverado evap question

Discussion in 'Maintenance' started by Dirttrax, Dec 16, 2016.

  1. Dirttrax

    Dirttrax New Member

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    I got 2011 silverado with 5.3. Got the notorious po446 code and couldn't fill up with gas. I replace the vent valve with the recommended gm parts, cleared the code. Now my truck isn't throwing any codes but I still can fill up with gas? Does this mean the charcoal canister is plugged too? Or would that throw codes. Any help is appreciated.
     
  2. WillyPaul

    WillyPaul GMFS Member

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    I get that code once in a while too even though I've replaced the evap canister. I'm starting to wonder if it's my fuel cap. What do you mean you can't fill up with gas?
     
  3. Dirttrax

    Dirttrax New Member

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    It won't take gas just keeps shutting pump off like it's full. I'm not getting any codes after changing the valve
     
  4. WillyPaul

    WillyPaul GMFS Member

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    mine has always done that since new, long before it was throwing codes. Usually pulling the nozzle out a few inches will take care of it.
     
  5. Dirttrax

    Dirttrax New Member

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    Trust me when I say I tried every way possible to put gas in it lol. I've tried the nozzle in all different positions but doesn't work. The most I've got in it was 10 bucks and that took about 15mins
     
  6. WillyPaul

    WillyPaul GMFS Member

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    Are you waiting until youre close to "E" to fill up? That's when mine does it the most. If I have over a 1/4 tank it's usually not a problem.
     
  7. Phildirt

    Phildirt n. fil-dert.

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    My NBS does the same thing. Replaced evap solenoid and it still won't fill. I get around $5 in it and then it's a half gallon, wait, repeat. On sensitive pumps I can't even fill it. Been working through a list on the truck and this is my next thing to fix. I was thinking it was something I did when I swapped out the fuel pump but it was doing it before that, just not as bad.
     
  8. benz88

    benz88 GMFS Member

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    Mine use to do that, but only at shell pumps for some reason. It fixed itself though
     
  9. Dirttrax

    Dirttrax New Member

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    Well yes but only because I bought the truck with a 1/4 tank lol. And I can't fill it up or I don't have that much time to spend at the pump
     
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  10. WillyPaul

    WillyPaul GMFS Member

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    Lol that's a bad habit to let it get low. Don't want to burn up your fuel pump. I try to fill up once I get down to half a tank.
     
  11. Dirttrax

    Dirttrax New Member

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    I do to with my other trucks. But guess you didn't understand I cant fill this one up lol
     
  12. John Clark

    John Clark GMFS Member

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    P0446 simply means a restricted or blocked evap vent path. It is set when the tank pressure is less than -10 inches H20 for as long as 30 seconds. Something is blocking the vent flow, which is obviously why you can't fill the tank. Remove the vent line going from the tank to the canister and check to make sure it's clear. Make sure the canister is clear and make sure the vent valve is clear. The connection at the tank, on the fuel pump, needs to be clear, too. If something is blocking that you'll get the code, as well so make sure that vent connection going into the tank is clear--air should be able to flow out of the tank but not back in through that connection.

    The reason your code hasn't come back yet is because the conditions for setting that code haven't been met. The conditions include fuel level between a certain level, coolant temp within a certain range, intake air temp within a certain range, and some others. Once all the conditions are met it will run the test and if it fails it will set the code. The light will go out on its own after it does three consecutive ignition cycles where the test is run and it doesn't fail.
     
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  13. Phildirt

    Phildirt n. fil-dert.

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    That's what I'm thinking is my culprit. thinking the vent line is kinked or pinched from when I put the tank back in. Just dreading unstrapping the tank to find out, it's such a bitch to get back in place with one set of hands.
     
  14. John Clark

    John Clark GMFS Member

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    Personally, I think it's easier to lift the bed. Remove four bolts on driver side, loosen ONLY the four bolts on passenger side, remove tailgate, unplug the lighting connector underneath the tailgate area and detach the filler neck and bracket from the top of the bed. Then just lift it up being careful not to scrape the back of the cab, and use a couple of 2x4's to hold it up while you check everything. It allows you to see everything in it's normal position.
     
  15. Phildirt

    Phildirt n. fil-dert.

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    Suburban...
     
  16. Dirttrax

    Dirttrax New Member

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    OK thanks. I'm pretty sure at this point the canister is clogged. The valve and the breather line were full of dry mud/dirt from previous owners.
     
  17. John Clark

    John Clark GMFS Member

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    The mud shouldn't be able to make it through the valve and into the canister, though. I suppose if someone had it in high water/mud when it was open that could happen.
     
  18. Dirttrax

    Dirttrax New Member

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    Maybe not but the valve was stuck open. I replaced it and hose and there are no kinks in filler hose so I'm leaning towards canister stopped up but haven't checked yet.
     
  19. John Clark

    John Clark GMFS Member

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    The valve is normally open and the PCM closes it when it needs to do the EVAP system check.
     
  20. Dirttrax

    Dirttrax New Member

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    Yes but it was stuck open and wouldn't close while doing the test. The new one closes and so far hast turned on light.
     

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