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Vented vs. Non-Vented Gas Cap

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Alex, Jul 10, 2002.

  1. Alex

    Alex Registered Member

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    Hi all, I want to replace the gas cap on my 91. The auto store indicated that there are two options. The first is a vented gas cap and other is non-vented. Does anyone have any experience on which one would apply? I would assume the vented, but then why would a non-vented be available. Thanks in advance.
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    You want non-vented. Vented is for vehicles without EVAP. (pre mid to late 70's I believe)
     
  3. 70~K5

    70~K5 1/2 ton status

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    So say someone removed the EVAP crap he'd run a vented cap right? /forums/images/icons/wink.gif /forums/images/icons/wink.gif /forums/images/icons/wink.gif /forums/images/icons/grin.gif /forums/images/icons/laugh.gif /forums/images/icons/cool.gif
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    unless the vent line in the engine bay was still there and not hooked to anything, like mine /forums/images/icons/smile.gif I wouldn't recommend that of course, but I haven't killed myself yet with it.
     
  5. TX Mudder

    TX Mudder 1/2 ton status

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    Dorian, you mean that the vent line that originaly went to the charcoal cannister on the driver's side of the core support?
    I'm asking because I still have that line. I just ran it to a plain breather. I'm not sure what kind of gas cap I have, but they came with the bed, look original, and the bed is an 87.
    Do I need to do something about the breather?
    -- Mike
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    Yep, thats the line I'm talking about...

    Well, the way I see it, if for some reason enough gas fumes came out the end, and the planets were aligned right, you COULD have an explosion. We all know how dangerous gas vapor is, so it just doesn't seem like the best idea. Any gas cap WILL vent, its just that it happens at different pressures. If you have an open line to the tank, (EVAP line) obviously the tank will vent through there instead of the cap.

    Sitting in the sun would tend to make the vapor in the engine bay worse, and although I won't take blame if anyones but my own Blazer blows up because of it, I think the danger is pretty slight.
     
  7. rampage

    rampage 1/2 ton status

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    Since you're in CA you need a non-vented gas cap. During your emissions testing they will remove your cap and check it to make sure it doesn't have a leak. That's where your evaporation caninster comes into play, which of course they make sure is at least present and hooked up.
     

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