Anyone vacuum diagram for 305 tbi 91 rs
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Joined: Jul 2008
Posts: 440
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From: Oglesby,TX
Car: 91 RS T-top
Axle/Gears: 3:42 fourth gen disk brake
Re: Anyone vacuum diagram for 305 tbi 91 rs
I have the vacuum diagram but i need to know what or where this goes to?
where does this go
http://i71.photobucket.com/albums/i1...ehart/idk2.jpg
http://i71.photobucket.com/albums/i1...carsvacuum.gif
Vacuum diagram
where does this go
http://i71.photobucket.com/albums/i1...ehart/idk2.jpg
http://i71.photobucket.com/albums/i1...carsvacuum.gif
Vacuum diagram
Last edited by weswisehart; Aug 31, 2008 at 07:48 PM. Reason: cleaned up the look
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Joined: Mar 2008
Posts: 67
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From: So. Cal
Car: 1991 Pontiac Firebird
Engine: 5.0L TBI
Re: Anyone vacuum diagram for 305 tbi 91 rs
I think that goes to the map sensor. If no one answers before tomorrow, I'll run out to my car and verify that for you. It's dark outside right now.
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Joined: Jan 2008
Posts: 112
Likes: 0
From: Fort Worth, Texas
Car: 1991 RS Vert
Engine: LO3, 305, TBI
Transmission: 700R4
Axle/Gears: 3.42
Re: Anyone vacuum diagram for 305 tbi 91 rs
I have the vacuum diagram but i need to know what or where this goes to?
where does this go
http://i71.photobucket.com/albums/i1...ehart/idk2.jpg
where does this go
http://i71.photobucket.com/albums/i1...ehart/idk2.jpg
It goes to a "T" that runs to the cruise control and the A/C controls.
It provides manifold vacuum to those functions.
The MAP sensor vacuum comes off the large port on the lower back of the TBI itself.
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Member

Joined: Jul 2008
Posts: 440
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From: Oglesby,TX
Car: 91 RS T-top
Axle/Gears: 3:42 fourth gen disk brake
Re: Anyone vacuum diagram for 305 tbi 91 rs
i have the one that goes to the map sesor connected its on the back of the tbi as Trick414 stated. so could i just plug it or should I run it? Also I have a hose that runs to a Thing rite behind my driver side head light any one know where that goes to? Thanks for the help Brian21 and Trick414.
Member

Joined: Jan 2008
Posts: 112
Likes: 0
From: Fort Worth, Texas
Car: 1991 RS Vert
Engine: LO3, 305, TBI
Transmission: 700R4
Axle/Gears: 3.42
Re: Anyone vacuum diagram for 305 tbi 91 rs
If you plug it (MAP sensor feed), you will run into problems with the computer, as it is looking for the values that come from that sensor.
Now, you can plug it if you are ditching the ECM and going to carb.
The other hose that runs to the "Thing" behind the driver head light. I'm assuming that is the hose that runs from the "A" port on the TBI (refer to your vacuum diagram you posted) to the charcoal canister?
Again, you can remove it and plug the TBI but you will start to have other problems.
Let me say it this way... all the vacuum and emissions sesnors/items/functions can be removed but you have to make some serious modifications.
In other words, you need to know what they are and what they do before you indiscriminately start to remove them.
Now, you can plug it if you are ditching the ECM and going to carb.
The other hose that runs to the "Thing" behind the driver head light. I'm assuming that is the hose that runs from the "A" port on the TBI (refer to your vacuum diagram you posted) to the charcoal canister?
Again, you can remove it and plug the TBI but you will start to have other problems.
Let me say it this way... all the vacuum and emissions sesnors/items/functions can be removed but you have to make some serious modifications.
In other words, you need to know what they are and what they do before you indiscriminately start to remove them.
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Joined: Feb 2025
Posts: 25
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From: The land of CARB
Car: 1991 Firebird
Engine: 305 TBI
Transmission: World Class T-5
Re: Anyone vacuum diagram for 305 tbi 91 rs
I was 1 year old when this thread was opened, and the photo does not link properly anymore, I just bought a 91 firebird a month or so ago and the previous owner plugged and cut some hoses that I am having trouble Identifying, could someone relink the diagrams?
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