I recently just got a 1983 4x4 and failed the first emissions test here is Washington DC. HC idle reading: 726ppm (limit: 220). CO2 Idle reading 5.29% (limit: 1.2) -- they only do a tailpipe sniff, no visual check.

It does have the smog pump removed by the previous owner. I have it, I just would need to track down some hoses. It does still have the ERG valve installed.

It has a new carb rebuild and plugs and wires in the last 6 months. The catalytic convertor looks old and maybe has an exhaust leak near the manifold.

I am wondering if a fresh ERG valve and new Cat would improves things enough, or if without the smog pump i am doomed. If I do spend $1,044 trying to fix it i get a 2 year waiver. So my back up is get a small engine leak fixed, a new ERG valve and some new exhaust and if it fails i get a waiver but at least have some new parts. The truck did pass Cali emissions a few years ago probably with the smog pump installed.

Thoughts?

 

Just look up a decent mechanic in your area that does emissions and have them do it.
I've used one that only charged me around $70 and once they had it tuned they even took it to the emissions place and got it passed for me.
Best of all, they wrote down all of their notes on what they changed so that I could do it myself the next year.
Usually, it's a matter of retarding the timing until it barely runs and with a Weber I have to put in the smallest jets that I have. I do not have any smog equipment installed. EGR blocked off, no pump, no reed valve, etc. Just a Weber 32/36, header, and a catalytic converter.

 

If you can get the CO (not CO2) down, it will drop the HC at the same time. CO is fuel delivery--so at 5% the carb is dumping too much fuel (especially at idle), could be just an adjustment on the mixture screw or the float may be too high. HC is the engines ability to burn the CO. So if it is dumping too much fuel the engine can't burn it all efficiently. The smog pump adds air (oxygen) to the cat convertor to get it hotter and make the cat more efficient. But it will have a hard time cleaning up that much fuel delivery. It will take a tech with a 4 gas machine to make the adjustments correct. Too lean and the engine will misfire and give you a high HC reading also

 

*edit Duh--you said right off the bat that you have the smog pump so I guess your truck did in fact come with one...

It's likely that your truck didn't actually come with a smog pump. The "federal" setup was a reed valve with tubes leading to both the air cleaner and the air injection manifold on the exhaust. It was the pulses between exhaust events that actually pulled fresh air through the one-way reed valve. I believe only California got an actual air pump. The one on my truck is very simply. In addition to the two large air tubes I mentioned, there's a third small vacuum fitting that runs to it from the intake manifold downstream from the carb, which controls the valve.

At any rate, if you're running a funtioning cat (yours probably isn't right now) you also need to ensure that your air injection is working properly to keep the cat alive. I'm going through the same thing right now. I've hooked my air injection back up (after desmogging and going Weber) but my cat is nonfunctional because--I believe--I killed it by both removing the air injection and allowing the carb to run too rich. If I can figure out why mine is putting out 2,600 ppm HC at idle, THEN I can fix that and put a new cat on, knowing that the engine feeding it is healthy.

 

...:p