Canister question
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Senior Member
Joined: Jul 2002
Posts: 815
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From: Toledo, OH
Car: '87 Formula
Engine: 350
Transmission: Auto
Canister question
It's been a longggg time since I've taken all this stuff out (some of it, I dont know why), and I'd like to know if anything needs to be done to hook the canister back up (traps tank fumes, correct?). I see here, looking at a diagram in my Haynes manual, that it originally ran to a Purge TVS (not sure what TVS is, but sure, I dont have it anyhow) and then to a Canister Control Valve (also done have). Since I no longer have these items, is it ok to just run a hose from the canister to a port on the carb?
I recently read about gas evaporating (almost in the gallon/week range!!) so I'd like to get this back on, trying to get my gas mileage up.
Thanks,
Ben
I recently read about gas evaporating (almost in the gallon/week range!!) so I'd like to get this back on, trying to get my gas mileage up.
Thanks,
Ben
Last edited by 87Formula4bbl; Jun 1, 2004 at 11:57 PM.
Supreme Member
Joined: Jan 2002
Posts: 1,322
Likes: 1
From: Bloomingdale,IL
Car: 91 RS
Engine: 305 Tbi (L03)
Transmission: 700r4
Tvs is a thermal vacuum switch.
You need both valves for you system to run properly. Otherwise you will have a vacuum leak at all times. You also need the valves to meter the amount of fuel vapor entering the engine.
You need both valves for you system to run properly. Otherwise you will have a vacuum leak at all times. You also need the valves to meter the amount of fuel vapor entering the engine.
Thread Starter
Senior Member
Joined: Jul 2002
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From: Toledo, OH
Car: '87 Formula
Engine: 350
Transmission: Auto
I'm assuming the TVS allows the canister to purge once it reaches a certain temp? I think the purge TVS sits atop the thermostat housing, right? I still have that on there, so no problems there. I think a vacuum hose runs into that from the carb, then from the TVS to the canister. I noticed the canister has a vacuum operated valve, which I assume allows it to purge when it sees vacuum (from thermal vac. switch).
Ok, no problems there, it looks then as if all I need is that Canister Control Valve, as seen in the pic. I'll go to the junkyard and pull that off. Man, I almost hate to rerun all these lines in my engine bay but hey if it means better mileage then its probably worth it. It was so cleeaannn looking tho
edit: Whoops, no vacuum line directly to TVS from carb, but I think that line feeds both the can. control valve and the TVS? Either way, is that how it works, still?
Ok, no problems there, it looks then as if all I need is that Canister Control Valve, as seen in the pic. I'll go to the junkyard and pull that off. Man, I almost hate to rerun all these lines in my engine bay but hey if it means better mileage then its probably worth it. It was so cleeaannn looking tho

edit: Whoops, no vacuum line directly to TVS from carb, but I think that line feeds both the can. control valve and the TVS? Either way, is that how it works, still?
Supreme Member
Joined: Jan 2002
Posts: 1,322
Likes: 1
From: Bloomingdale,IL
Car: 91 RS
Engine: 305 Tbi (L03)
Transmission: 700r4
Thats pretty close to how it works. The purge valve is controlled by a solenoid that is ecm controlled not by the tvs. The tvs is just a valve that only allows the system to purge once it has reached a certain temperature.
Thread Starter
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Joined: Jul 2002
Posts: 815
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From: Toledo, OH
Car: '87 Formula
Engine: 350
Transmission: Auto
Does anyone know if it would be a bad idea to cap off the fuel line where it's supposed to go to the canister? I would think....yes....but, I'm not positively sure how the gas tank works with pressure.
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