86 pick up 22r carb, was running and idling fine around 1100 rpm was the normal idle. Made a right turn and noticed rom dropping, this is after about 30 miles driving street and freeway. Truck will turn off won’t idle. Diffficult to keep the idle low with pedal, with ac on the idle jumps to about 1700 and stays on but isn’t constant like before it will drop from 1200 to 1700 with ac on.
What should I check first? This is a smog legal truck and I am trying to get some insight on what to check or what is it that keeps idle constant.

any help is appreciated

 

Anyone knows where this connects to? It is currently open

 

From picture above, the white piece was open. Other fitting had a hose to it

 

 

From the picture above, I checked where it connects to and it already has a hose connected there at the bottom portion, wonder if it’s routed wrong. I wouldn’t doubt it as this truck has a a lot of messed up electrical wiring I wouldn’t doubt vacuum lines as well. What would you guys recommend for a manual shop? Something that has wiring diagram also, looks like I’ll be putting lots of work into this little truck, luckily I like driving it. An update on the idle,
I drove the truck and really pushed it in 2nd to around 4500 rpm then it seemed to idle again but was somewhat choppy and not stable like I would like so I think that rules out a clogged port in the carb, which is what I felt might have happened. Someone had suggested egr valve could be the cause, the fact it turns on and runs tells me there’s some mechanical component that helps with idle or something that isn’t functioning. When fully cold the truck idles fine, seems as though soon as the choke turns off the idle gets choppy and really low.

 

Did you get the other end of the MC big hose and the vacuum line connected to the underside of air cleaner? Did it make a difference?

Use this link to go to the vacuum piping diagram for your model. Using these diagrams helped me when I replaced vacuum lines and after rebuilding the carb even though I labeled all the lines.
https://www.japan-parts.eu/toyota/eu...ol-engine-fuel

Post with link to manual downloads
https://www.yotatech.com/forums/f115...manual-156129/

 

Just to update this old thread, I have fixed the idle issue and it seems to have been electrical. Since I got the truck the battery has been weak, basically dead after 2 days or so. I tried keeping it charged or but it would still die until it finally reach 8v and wouldn’t charge anymore.

upon replacing the battery, I found the ground cable barley connected and it basically fell apart when I removed it from the battery. So I bought a new battery, I made a new ground cable with some copper connectors and 8 guage wire and now it works fine. Only thing I can think of is because the previous owner didn’t have the battery hold down it was jimmy rigged hold down, when I was driving the battery moving caused the ground cable to basically break, causing the bad idle. Just wanted to sum up how I fixed this issue. That said the truck still needs quite a bit of attention so I’ll work on that next.