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Discussion Starter #1
Does anyone know where I can get a good labled picture of the 220 TBI? Basically, I need to know where all the hoses go..
 

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life begins @ 20 psi
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If you are talking about all the vacuum lines on the back, check out the VECI (Vehicle Emission Control Information) sticker on the fan shroud. HTH's

Mike Campbell
 

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You mean 262 TBI right?

sseries.org has some pic of all the 4.3L engines in a sticky at the top of the 4.3L tech forum.
 

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Never-Ending Project
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The model number of the TBI used on the 4.3L is 220. There are three ports on the front, left-to-right they are: EGR solenoid, PCV (pass side valve cover), vapor canister. There's one port on the back, it's for the MAP sensor.
 

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Discussion Starter #6
I saw four, I take it there is two on the right go to and from the vapor canister?
 

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Most all the 4.3's that have the injectors incorporated into the
Throttle Body itself are Rochester 220 TBI's.
 

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Discussion Starter #8
and???? How does that apply to what I am looking for??
 

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Maybe this picture will help:

1- EGR solenoid
2- PCV
3- Vapor canister
4- some 220 TBI's have a plug here, my Holley did. I just put a cap on it.
 

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Discussion Starter #10
My 220 Has a port at area 4, do you happen to know the purpose of it or where it is to be attatched?
 

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Never-Ending Project
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What year motor do you have? I might have a vacuum diagram for it. If all you have is the MAP, PCV, EGR, and EVAP then you can just plug that port.
 

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Discussion Starter #12
The port is plugged at the moment, but when I pull the plug, the engine picks up idle and runs smoother, hence the quest to find out exactly where it goes to. Another thing I noticed, there is three ports on my Vapor Canister. One going to the gas tank, one to TBI, and one port that is not used, but in Chilton's it is.. It is a 1991. I don't know if the engine is the same year or not, but I am going to assume it is.. Thanks for all your help thus far, it has opened up a few ne doors for me..
 

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Doesn't that one in area 4 go to the thermal switch in the air cleaner that opens the valve to let warm air in from the tube connected to the header during cold startup.
 

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Here's a 1991 vacuum diagram:

Mine is a 91, but this is the diagram I have (with the LLW code):

The idle will always pick up with a vacuum leak, since the MAP voltage will change and fool the ECM to thinking the motor is under a load. If you have a vacuum-operating THERMAC air cleaner, then that's where it would go to. Mine doesn't use a vacuum line, but I have an 360 open-element K&N anyhow.
 

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Discussion Starter #15
Ahh hah, Well I guess the port is going to remain plugged then, I have a Edelbrock cleaner on there, and the Thermac has not existed since I bought the vehicle. Thanks for all the help..
 

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I need some help with my vacuum lines too. I have the a W code 91 4.3. What I am confused on is the vacuum tank (black ball) is routed to one of the 4 lines coming from the tbi (which ones I don't recall). And there is this bigger vacuum line coming from a little port in the intake, then a check valve, and a couple t-fittings that connect the ball to one of the other lines. And then the cruise is somewhere in there. I was reading that the thing I called a "little port" is supposed to be the vacuum supply for the ball, cruise and ac vent control, and entirely seperate from the emissions system. Another thing I found is two air lines stuck behind the engine that i can't figure out where they come from, but I suspect one is for the hvac controls, which don't work. There is also some kind of vacuum unit similar to the cruise servo hidden in the passenger fender with avacuum line too. I have never seen anything like it, but it all looks stock!
 

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Here's a 1991 vacuum diagram:

Mine is a 91, but this is the diagram I have (with the LLW code):

The idle will always pick up with a vacuum leak, since the MAP voltage will change and fool the ECM to thinking the motor is under a load. If you have a vacuum-operating THERMAC air cleaner, then that's where it would go to. Mine doesn't use a vacuum line, but I have an 360 open-element K&N anyhow.
The 1991 S10 was a transition year. The early S10 without CTF had a THERMAC and the late S10 with CTF did not have a THERMAC and the TB did not have a vacuum port nipple for the THERMAC. The air cleaner on the late S10 with CTF did not have a THERMAC.

CTF means "Corporate Test Facility". It is where the engineers made a mid-production design changes. Example: If the console opens from the side, the S10 is with CTF.

You must be aware if your S10 is CTF or not CTF when you order some parts. Some parts will not interchange between CTF and non-CTF vehicles.
 
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