My truck recently failed the emissions test, and I'm not sure what needs to be done. I know the engine was "liberated" from a lot of it's original emissions plumbing by a previous owner, and now I need to get enough of it re-installed to register it. Were '81s originally fitted with an air pump? If so, did the original exhaust manifold have fittings for air injection? From the number of plugged vacuum lines under the hood, anything is possible. Thanks in advance for any light you can shed on this.

'81 Flareside
3.08 gears
33"/31" tires
300/4spd
(Formerly Baitboy)

 

Join the club my friend. There is a lot of folks trying the repair the handy work of someone else that had "connections."
Yes, the 1981 had a thermactor (air) pump on it. It could inject air into a number of things : 1) Some early thermactor systems (like the one on my '79) pumps air soley into the spacer that sits between the carb and the intake. There's a hole in the "plenum" that allows air from the check valve into the duct in the intake that leads to chambers in the exhaust manifold. 2) Other systems inject air straight into the head immediately after the exhaust valve (there's small threaded holes in the head) with an air manifold. 3) I think the later is also combined with a switching valve that allows the air to be injected into the catalytic converter during warm operating conditions. There's also a dump valve that allows air to be routed to the atmosphere during deceleration and idle. You definelty have some homework to do the figure out what you need. Hopefully, there's a vacuum routing schematic on the inside of the hood to help aid you in plumbing the truck correctly.

 

From the location of the plugged vacuum lines, it looks like mine probably had the air pump connected to a port below the carburetor. There's a stub of what looks like heater hose that is connected there, with a plug in it. (I don't know if it was artistic expression, or what, but the person doing the "air pumpectomy" used a spark plug to plug the hose!) I do have a schematic under the hood for emission stuff, but the abbreviations are greek to me. I've tried a number of sources to find out what all might be missing, but since there were some running changes in manufacture, there isn't a firm answer on '81s. A local garage has a book that tells what equipment was installed, based on the date of manufacture, so that should at least tell me how much work I have ahead of me.
My registration expires at the end of June, so I've got a little time to get things sorted out, but the air quality folks up here in Seattle are a little unforgiving when it comes to icky air coming from your rig.
Besides the money and time I'll need to spend to get it right, I'm hoping the changes don't adversely affect the way the truck runs. My gas mileage is decent, (14.5 city/17.5 hwy).
Every dollar I put into the truck, is another dollar I don't get to put into the boat.
I'll keep you posted on the results of this odyssey.

'81 Flareside
3.08 gears
33"/31" tires
300/4spd
(Formerly Baitboy)

 

Haynes publishes an emissions book that will give you a good overview of the different elements of the emmissions system works. So, it doesn't sound like you have air injection holes threaded into the head or some elaborate air manifold fixture that runs to the catalytic converter. Given that info...your air pump plumbs straight into the plenum. There should be a check valve that threads into the plenum before the hose with the handy artwork. This keeps the flow of air in one direction and keeping exhaust from backing into your air pump. In between the air pump and the check valve you'll need a bypass valve that dumps the air into the atmosphere from the pump. Mine is contolled by ported vacuum of the carb. Some trucks use a vacuum control valve. A temperature sensative element in my air cleaner also

 

I do appreciate your response. I had the tech at the local garage check his book to see what the state requires in the way of emissions hardware, and the only major pieces missing are the air pump, the air management valve, and the air pump bracket. Other than that, running vacuum lines to all the components that are currently plugged is all that is required to get me back to where I need to be. The biggest problem, according to his scope, to being clean enough to pass the emissions test was an internal problem with the carb itself, so just last night I put on a rebuilt unit, and am hoping that will allow me to pass the test outright. If so, I don't need to worry about the air pump, etc. If the new carb doesn't do the trick, then I'll need to re-install the pump, etc., in order to be in compliance.
Up here, the state requires that the truck either passes the clean air test, regardless of equipment that is installed, or you must spend up to $150 to improve air quality. That would give you a waiver, which also allows you to register for two years, but they conduct a visual inspection, to be sure all components are installed and working. If I can pass the test outright, they don't bother looking under the hood.
Going to a boneyard to get the missing hardware doesn't sound like an insurmountable task, but it'd be nice to just pass, and not have to mess with it.
Once again, I do appreciate your help on this.

'81 Flareside
3.08 gears
33"/31" tires
300/4spd
(Formerly Baitboy)

 

 

It seems like a lot of work but you also have to think of the affects that a clean (accourding to Govt. standards) truck's exhaust has on the environment compared to one that isn't street legal. A little work to make the air and earth in which we roll in our trucks nice for the future. Now if we could somehow get those big 3 in "DETROIT" to come out with a truck, or car, that is 99% emissions free but still has 300 hp and tons of torque, awe what a world it would be! HA