Okay so got my Rochester 4 barrel quadrajet carb tuned and adjusted which helped a lot with my gas mileage.No leaks or anything under the carb. however they said I need to replace the purge valve which will cost like 135 bucks for them to do it. Is it easy enough to do it myself of should I let them do it? The check engine light is still on maybe cause it's still running a tiny bit rich still? The codes last time I checked were for the O2 sensor, which I replaced already, throttle position switch which is working otherwise the wouldn't be able to tune the carb correctly so I've heard, and that the carb was running very rich.They said its 75% done and only need to do the purge valve to make it perfect. So I'm guessing it's just purge valve that's keeping the light on or maybe the tps? But they wouldn't be able to tune the carb correctly if the tps wasn't working So I've heard so I'm a bit confused as to why this light is still on. Someone help!

 

I believe the purge valve is the one that's just connected to several hoses. Look at your catalyst decal; it may identify it.

A TPS can be bad or misadjusted without setting a check engine code in my experience.

You need just a paperclip and your key to check the codes using the under-dash ALDL terminal. Post what they are after removing the ECM fuse for 30 seconds and going and driving it a while.

 

Okay first what's a catalyst decal? If you're correct would it be easy to replace by myself? I'll check the codes again when I get a chance, however if the throttle position switch is not bad and just needs to be adjusted how do I go about that exactly.

 

Catalyst decal is placed on the fan shroud (83) or core support area. I can't find mine right now.

Yes it's an easy replace.

TPS adjustment is a 2.5mm socket tool. Pics to come.

 

The purge valve is only attached with vacuum hoses in front of the carb. It allows vapors from the charcoal canister to be diverted into the carburetor under certain conditions (low vacuum, full operating temp). Replacement is incredibly simple.

It shouldn't set a code unless it's failed and causing a vacuum leak. In that case it can be temporarily blocked off. An '83 wouldn't know whether the purge valve was hooked up or not.

The carb can be adjusted with a failed TPS unless it's failed to read high. Many fail so that the signal to the ECM is no longer linear with throttle opening.

If the check engine light is still on find out why. It ain't fixed yet.

 

Well my carb was reading very
High for something I don't remember what but in order to pass inspection it needed to be at like 1.30 or something like that and it was reading 10.75 or over that so they tuned it to the point that it went down to 2.35 or so. And then they tested the purge valve cause it wouldn't read any lower and found out if they unhooked the purge valve it read a lot lower and was better and so it is bad and that just needs to be replaced. Anyone know how much a purge valve would be? And maybe a pic of one on the carb so I know exactly where it is

 

Capped closed.
Uncapped; Thexton tool (2.5mm hex) applied.
Setting for LG4/L69.

 

And I don't know what piece you may (or may not) need to replace to improve emissions, but it's probably the switch (threaded into intake manifold) or the just-smaller-than-soda can device with 4 or 5 hoses. See attached; should be close to your 83. Good luck.

edit: added another pic.