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Strong Gas Smell

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by johnny reb, Aug 2, 2001.

  1. johnny reb

    johnny reb 1/2 ton status

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    Every so often while I'm driving I'll get a strong odor of gas fumes that seems to be coming through my vents. It's most noticeable after I accelerate hard and then let off the gas. It lingers for a few seconds then it goes away. I'll also smell it occasionally after I make a sharp turn as if gas is spilling from somewhere. I'm also starting to get a small backfire from the exhaust when decelerating. Don't know if this has anything to do with it. Where should I look?

    1986 K5, New GM 350, Edelbrock Intake, K&N Air Filter, Flowtech Headers, Dual 3" Exhaust, 33" Pirelli Scorpion AT, 700R4, 3.42 gears
     
  2. Tuskadero

    Tuskadero Registered Member

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    Sounds like your cat is shot on your exhaust, I have the same problem and that is the issue good luck,

    Heather
     
  3. 83ZZ502_Jimmy

    83ZZ502_Jimmy 1/2 ton status

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    You could have a bad charcoal canister. It lets the engine burn the gas vapors coming form the tank. It's for emissions stuff. It should be located by the drivers side headlight in the engine compartment. It is tied into the engine vaccum and could conceivably work its way into the vents. A vaccum loss can cause a backfire. I'd check all lines and if you can get rid of the canister without failing emissions, Do It!!

    '83 GMC Jimmy 4x4 ZZ4 Crate Motor
    '83 Chevy K20 Sand Drag Racer, 578 RWHP
    '94 Impala SS
    '01 Chevy 2500HD 4x4 w/8.1L & Allison Auto
     
  4. muddin4fun

    muddin4fun 3/4 ton status

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    Do you black smoke out the back of the pipes? My first guess would be that it's running rich.

    I've got a mind like a . . . a . . . what's that thing called?

    <a target="_blank" href=http://www.geocities.com/muddin4fun79blazer/>http://www.geocities.com/muddin4fun79blazer/</a>
     
  5. sapper

    sapper 1/2 ton status GMOTM Winner

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    look in your air cleaner. my 82 did the same thing and i found gas literally pudled up under the cleaner.

    We are surronded. That simplifies our problem.
     
  6. johnny reb

    johnny reb 1/2 ton status

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    Well, I already failed emissions so that's not a problem. If I remove the canister what all does this involve? Do I just remove the lines that go to it? Do I have to plug them up?

    Muddin4fun - I have no black smoke from the exhaust. However, I also have no AIR pump which was removed and never replaced when I put headers on. This is why I failed my emissions test and also why I have a strong CO smell from the exhaust.


    1986 K5, New GM 350, Edelbrock Intake, K&N Air Filter, Flowtech Headers, Dual 3" Exhaust, 33" Pirelli Scorpion AT, 700R4, 3.42 gears
     
  7. realsquash

    realsquash 1/2 ton status

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    Did you have beans for supper? Just kidding. I would check to make sure your fuelpump is ok.

    Squash
    <a target="_blank" href=http://www.trailrunners4x4.org/users/realsquash>http://www.trailrunners4x4.org/users/realsquash</a>
     
  8. 83ZZ502_Jimmy

    83ZZ502_Jimmy 1/2 ton status

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    Yeah, pull off all th lines going to it and follow them to where they go. Then pull those ends off and plug 'em. It should not be too hard.

    JH

    '83 GMC Jimmy 4x4 ZZ4 Crate Motor
    '83 Chevy K20 Sand Drag Racer, 578 RWHP
    '94 Impala SS
    '01 Chevy 2500HD 4x4 w/8.1L & Allison Auto
     
  9. beater74

    beater74 1/2 ton status

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    no no no plugy that is your vent line for your tank. you my use your canister but don't plug it put a vent cap on it like on your diff, or use a K&amp;n vent frilter. get some gas smell but it's comin from my carb, smell your air filter for a STRONG gas odor it could be your carb.
     
  10. 83ZZ502_Jimmy

    83ZZ502_Jimmy 1/2 ton status

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    I stand corrected. I forgot to mention that you need to put a vent cap on the line to the gas tank. If you don't bad thing can happen, like your tank could collapse.
    Sorry for the confusion.

    JH

    '83 GMC Jimmy 4x4 ZZ4 Crate Motor
    '83 Chevy K20 Sand Drag Racer, 578 RWHP
    '94 Impala SS
    '01 Chevy 2500HD 4x4 w/8.1L & Allison Auto
     
  11. dyeager535

    dyeager535 1 ton status Premium Member

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    You can remove the cannister, you CAN plug the lines, but you have to go to an earlier cap that is vented at MUCH lower pressure. I should have run evap, because if gas fumes are going to escape anywhere (such as with a vapor) I don't want it anywhere near my hot exhaust, or the engine. I dont think venting the lines is a good idea at all, the gas vapor is much more dangerous than liquid gas.

    With that said, I've been running mine with the tank fuel vapor line to the engine bay wide open for about 4 months. : )

    I do plan on at least plugging it entirely, or going with a similar evap cannister setup as stock, but with just a line straight to carb from the cannister. (gas might as well get to the motor, won't hurt but to improve MPG!)

    The EVAP filter is replaceable AFAIK, and most of the lines could be pulled and checked for blackage by just blowing air through them. (lots of thermal switches and such inline, but those can be easily tested too)

    Dorian
    My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</a>
    No anti-theft measures on your truck? No pity when its stolen
     

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