What Is This?
 

https://cimg1.ibsrv.net/gimg/www.yot...70b4efda9c.jpg
I was pulling out some vacuum lines and removed this from the rear of the upper plenum. There were only 2 vacuum lines connected to it. Should there be a third one or should it be plugged up? Truck is an 89 pick up 4x4 22re 5 speed. California emissions.

Exactly where did you remove it from?
I see one on mine. 2 lines to it, the third plugged. Does your truck run with it unplugged?

Cool.
Yes, most likely the unplugged port is the problem. That's a big vacuum leak. That unused port could be used for added things like a vacuum gage. For now, connect a short hose to it, fold other end onto itself and tie-wrap. That would be an effective plug.
I'd call that thing a vacuum manifold.

C'mon guys. These parts have names. Strange ones, but who am I to judge.

Filter, Gas, No. 1 https://parts.lakelandtoyota.com/p/T...091711027.html

That part is just a port for vacuum to run the PAIR, A/C Idle Up, Fuel Pressure Up, Cruise Control and ADD. If you don't have all of those, you may only be using two of the three ports. In which case the third port MUST be plugged or you just have a big vacuum leak.

Dorman makes an inexpensive assortment of caps that you can get at most auto parts stores. Or you can fold over a piece of vacuum hose as a temporary fix. Assuming you have a piece of vacuum hose, and you're not making a special trip to buy it.

Thanks for the info! I'll plug that up and see how it runs. This truck is bare bones, so no AC or cruise which would explain the extra vacuum port.

i know you now know what this is but did your truck have the vacuum diagram under the hood?

Yes, its on the hood.

Could you possibly show me a picture of the third plugged hole? I'm curious to see what its supposed to look like.

The gas filter is near the center on all the ones I've seen.

It will show if it had one, two or all three nipples used in the system.

The third one on my RET is for the digital dash boost guage.

I don't recall what is used on the 94.

The unused ones just have a rubber cap on them, you can get these in an assortment from the parts store. The ports are all the same, it won't matter which you put the cap onto.

By "near the center," I assume co_94_PU is referring to the center of the vacuum sticker.
Like these:
https://cimg7.ibsrv.net/gimg/www.yot...3bc6e2f6e4.jpg
https://cimg8.ibsrv.net/gimg/www.yot...afdaeb5b8d.jpg
On my '94 with the 3VZE, the sticker doesn't show the ADD or the Cruise Control. So I have all three ports in use, even though the sticker only shows two.

Well I obviously need to get a reprinted sticker..
https://cimg4.ibsrv.net/gimg/www.yot...f95a81baad.jpg

Tool this picture then started to wipe the smutz off and the print came with it..

These show the emissions stuff only iirc ??

I have the cruise control, the digital dash, and vacuum tank hooked to my gas filter.
https://cimg1.ibsrv.net/gimg/www.yot...515e2f1637.jpg
Top is CC, bottom is dash gauge, and the one hiding is the vacuum can (tee's off to things like the FP regulator).