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Can't Pass Emissions

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by NateAz87k5, Feb 9, 2002.

  1. NateAz87k5

    NateAz87k5 Registered Member

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    Can\'t Pass Emissions

    I can't get the Blazer to pass emissions... The pressure tests that is. I can't find any leaks in the line from the canister to the tank. I replaced all of the hoses(including the filler) and still cant pass. I've got a bad feeling that I might have a leak at the fuel pump. If this is the case is there any way around this? Any tricks if you will? Can I just clamp off the filler tube and smaller gas line next to it so the pressure doesn't go into the tank when testing? Don't really have the time nor $$$ to repair it right now and I need to pass. Thanks for any help. I live in AZ if that helps. 87k5
     
  2. dysphemism

    dysphemism 1/2 ton status

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    Re: Can\'t Pass Emissions

    They make this stuff called gauranteed to pass. I guess you put it into your tank, use all the tank, and then refill and you will pass the test gauranteed. Can't be too good for your engine I'd bet but you might want to try it. I have a bottle handy just in case my K5 isn't up to passing.

    1986 GMC Jimmy 6" springs 3" body, 38/15.5/15 Swampers, 14-bolt FF rear, Dana 60 front, 1991 front-end.
     
  3. ChevyCaGal

    ChevyCaGal 3/4 ton status

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    Re: Can\'t Pass Emissions

    All Guaranteed To Pass is, is a bottle of rubbing alcohol in a fancy can so they can charge ya more $$ for it... [​IMG]



    <a target="_blank" href=http://www.chevycagal.homestead.com/steph.html>Steph's Webpage</a>
    "Grace is knowing when to be a lady and when to say "Ah, bite me, outta my way!"
     
  4. NateAz87k5

    NateAz87k5 Registered Member

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    Re: Can\'t Pass Emissions

    The blazer passes the emissions part of the test. It doesn't pass the pressure test. this is a test where they place a cap on the tank (where the gas cap goes) they pump in air pressure to see if it will hold in the tank up to the line before the cannister. If the pressure doesn't hold you fail. This is what I am having a problem with... Thanks
     
  5. Corey 78K5

    Corey 78K5 1 ton status

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    Re: Can\'t Pass Emissions

    I did a shackel flip on mine about two years ago and in the process I droped the fuel tank for safty sake (sparks and fuel dont mix) and when I saw the fuel lines going in and out of the tank I was shocked they were so rotted and split I guess that explained why I always got a gnarly head buzz when I would do some side hilling. Cost about $1.50 for some new fuel line to fix couple diffrent sizes in there but mine is also a 78.
    Corey 78K5
     
  6. K5 NUTT

    K5 NUTT 1/2 ton status

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    Re: Can\'t Pass Emissions

    Gaurantee'd to pass is for the tail pipe...and the 87 fuel lines are all steel or braided steel...there is a rubber o-ring that seals the sending unit to the tank lock ring...ask haulgas about this...he had the same problem not so long ago....hehehe.

    Azblazer

    1979 K5 350 TBI
    1976 K5 Chalet
    If it ain't got arizona pinstriping.....you ain't wheelin the pee outa her!
     
  7. Headbanger

    Headbanger 1/2 ton status

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    Re: Can\'t Pass Emissions

    What the heck kind of test was that? California doesn't even have a test like that for smog! The only thing we check are the hoses,canister condition,fuel leaks and the fuel cap pressure test.
     
  8. Haulgas

    Haulgas 1/2 ton status

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    Re: Can\'t Pass Emissions

    I had the same thing happen to me . Mine was the filler pipe was cracked where it goes into the tank. I drop the tank and was going to have it rewelded but then I found my baffle was broke. I bought a new 31 gal tank from Rockauto.com for 107.00 and that took care of that.

    IT'S NOT JUST A J**P THING AND I DO UNDERSTAND
     
  9. bigdaddy89

    bigdaddy89 1/2 ton status

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    Re: Can\'t Pass Emissions

    Mr. Nate,

    I have been going through this same exact thing for the last few months. I have replaced every hose and clamp along with the bushing under the sending unit. I am dropping it off to a friend of mine on Fri. who works at the dealership to see if he can find the problem. I will let you know the verdict. Give me a call this week. David

    GOT ROCKS?
     
  10. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: Can\'t Pass Emissions

    Well, by deduction, the fuel lines aren't the problem, right? (vehicle runs don't it?) If the problem lies in the cannister purge setup, then there is probably a check valve, vacuum switch, or solenoid that purges the cannister when the vehicle is moving, but that SHOULD be "shut" when the vehicle is not running or at idle. (hence a stuck open valve leading to failure)

    A real quick fix would probably be to find the vent purge line from the tank to the cannister (IIRC, mine was accessible right near the steering gear box) and plug it. I wouldn't run that way long, but if the gas cap is working correctly, it WILL vent before the tank ballons.

    I'm just thinking out loud here, (since no one has posted a definitive answer) but the tank vent comes off the sending unit, (not checked in any way, its a vent) all the way up to the front of the truck, and from there...well, not sure. I don't believe the Evap cannister is "air tight" so I would have to believe, if the test is with pressure, there must be a "valve" in the engine bay that allows fuel tank purge ONLY to the evap cannister when necessary. (if it wasn't before the line reached the cannister, I believe a pressure test would never work) Since those kinds of "valves" are usually run by vacuum or temp, I'd never suspect the valve to be anywhere except under the hood. Perhaps though, that the Evap cannister eventually DID get airtight, and the Evap cannister purge valve (from evap to TBI unit or air cleanerlikely) in your case has failed. I am pretty sure though, that the Evap cannister MUST be able to vent, in case of problems.

    Follow the line from the tank to where it goes. Heck, you can probably plug the line right where the tank line goes to the frame, since its not a high pressure line.

    I guess it could be fuel return line as well causing the problem, but I'd suspect you'd have a strong gas smell if that were the case.

    I'm not really suggesting you plug the line just for the test, then undo it, I'm suggesting that you plug the line if you must pass right away, you WILL fix the real problem after passing, and that you actually determine what the problem is before just blindly plugging lines. I'm just throwing out what I know and suspect, hopefully blindly guiding you to your problems cause : )

    Dorian
    My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>www.dorianyeager.com/index2.html</a>
    Why insist on counting when the ring gear has the tooth counts stamped in?
     

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