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What Does Air Pump Do?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by johnny reb, Jul 3, 2001.

  1. johnny reb

    johnny reb 1/2 ton status

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    What is the purpose of an air pump?

    I recently failed my PA emissions test. Tech said it was probably because I don't have an air pump. When I had emissions test a year ago I still had a tired 305 in it and my CO% was around .02% at idle and at 2500 rpm. I'm guessing that the 305 did have an air pump on it. Now with my new GM 350 my CO% jumped to 3.5%. 1.20% is the limit in PA. When I had the new 350 installed I also had headers put on and left the air pump off. I'm not about to have an air pump put on, I'm just going to drive it and take my chances. I just don't understand how CO% is affected by the air pump.

    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. 87K54WD

    87K54WD 1/2 ton status

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    Here is a link that you might find useful: http://www.weekendmechanicsclub.com/ACDelco/vobeng6.htm

    It has some drawings that explain in detail how some systems work. The main point I got from it was:
    "During normal combustion in an engine, some hydrocarbons in the fuel are not completely burned and, in the absence of sufficient oxygen, carbon monoxide is formed. Exhaust gas, as it leaves the cylinders, is hot enough to continue burning if more air were available.

    The Air Injection Reaction (AIR) System helps to reduce the amount of unburned hydrocarbons and carbon monoxide in exhaust gases by injecting air directly into the exhaust."

    I don't know how to make the hyperlink "clickable."
     
  3. HarryH3

    HarryH3 1 ton status Author

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    Clickable:

    <A target="_blank" HREF=http://www.weekendmechanicsclub.com/ACDelco/vobeng6.htm>http://www.weekendmechanicsclub.com/ACDelco/vobeng6.htm</A>

    <font color=black>HarryH3 - '75 K5</font color=black>
    <A target="_blank" HREF=http://www.angelfire.com/super/ThunderTruck>http://www.angelfire.com/super/ThunderTruck</A>
    It's a great day to be alive...
     
  4. OneInTheSun

    OneInTheSun 1/2 ton status

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    For what it's worth -
    My AIR pump froze up so I took off the belt before taking it in for inspection and thanks to the new bullsh!t PA "visual" emission inspection law, I had to put on a new pump. I got the emission readings before and after (and I don't have them in front of me), but my blazer passed no problem the first time and the second time wasn't all that much lower. So, the AIR pump will reduce emissions, but is that really the culprit? I realize we're talking two different engines here, but can the pump possibly take you from 3.5% to 1.2%? Just a thought.

    <font color=blue>Rob
    85 K5</font color=blue>
    [​IMG] 24 beers in a case, 24 hours in a day - Coincidence?
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    Depending on the test, leaning the carb mixture at idle will lower your co levels if done right. I too passed without AIR nor a cat on my '83, but I made sure it was in good tune (plugs, wires, cap, rotor, rebuilt the carb) before I went and tested it.

    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
     
  6. MaxCrack

    MaxCrack 1/2 ton status

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    It pumps air (oxygen) into the exhaust, which is used either immediatly by the hot exhaust or in the catalytic convert to convert CO to CO2.

    That's because I'm the devil.
     

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