Vacuum line routing help needed.

[LARIAT 85]

You cab hook the bowl vent directly to the cannister. The purge valve isn't needed.

"The purge valve isn't needed?" Of course it is needed. That is, if you want the evaporative emissions to actually work.

The fuel vapors captured within the charcoal from the vapor canister can never be drawn out and pulled into the intake for burning without a purge valve in place and connected to a manifold vacuum source.

The vapor canister will eventually become saturated, and cease to work.

Much like a PCV valve, a canister purge valve is calibrated differently for an inline six engine compared to a small block V8 or even a big block V8. And much like the PCV system, the evaporative emissions system doesn't cost any horsepower or have any adverse affects; it only helps.

 

[LARIAT 85]

Dave: I have a valve from my '84 351W that I think served the same function as the one you need, although it does not look anything like the one pictured. I know it was attached between the bowl vent and the charcoal canister.

It is a cylinder 1" in diameter and 1 3/8 " tall, with ports off opposite sides of the cylinder, one higher and one lower. There is a vacuum port off of the bottom, and no "engineering numbers" any where to be seen: just an arrow pointing to the upper port with the word "carb" and the Ford oval logo.

If it sounds like you could use it, let me know and I will mail it to you. I kept most of the little vacuum valves when I switched over to Duraspark and non-feedback carb. but I will probably never use them.

What you are describing is the thermostatic vacuum bowl vent valve. This vacuum-controlled valve was used in 1984 and 1985 and replaced the earlier electric bowl vent solenoid valve for most models that used the small block Windsor engine.

One end (CARB) had a rubber hose that connected to the external bowl vent on the carburetor and the other had a rubber hose that connected to the canister purge valve. The canister purge valve connected to the vapor canister by a rubber hose. The vacuum port off the bottom of the thermostatic vacuum bowl vent valve connected to a manifold vacuum source. Anytime the engine is running manifold vacuum is produced and the valve closes, sealing off the external carburetor bowl vent. When the engine is off and manifold vacuum is no longer present, the valve opens back up to vent the fuel bowl to the charcoal canister.

Capiche?

[FuzzFace2]

What you are describing is the thermostatic vacuum bowl vent valve. This vacuum-controlled valve was used in 1984 and 1985 and replaced the earlier electric bowl vent solenoid valve for most models that used the small block Windsor engine.

One end (CARB) had a rubber hose that connected to the external bowl vent on the carburetor and the other had a rubber hose that connected to the canister purge valve. The canister purge valve connected to the vapor canister by a rubber hose. The vacuum port off the bottom of the thermostatic vacuum bowl vent valve connected to a manifold vacuum source. Anytime the engine is running manifold vacuum is produced and the valve closes, sealing off the external carburetor bowl vent. When the engine is off and manifold vacuum is no longer present, the valve opens back up to vent the fuel bowl to the charcoal canister.

Capiche?

Got it!

I plumbed this up this morning (2am could not sleep) and the way I did it was.

carb bowl vent> hose> valve with "carb" pointing to carb> hose to canister.

This hose stock had a "T" and based on the sticker on the radiator support went to the PCV upper nipple so that is how I ran it.

Now this valve with "carb" on it, I could not blow air thru it from either side so I took it apart. It looked clean inside so I put it back together and installed it.

So the way I see it with motor off no flow, you say it should?

I am not too worried on the carb side as it has a bowl vent under the filter assy. so fumes should stay there. The tanks go to the canisters and when the motor is running should get pulled in and burned.

Also because they are in a closed system I should not get any fumes from that when the motor is off either....I hope lol.

If you could not tell I did not want to smell gas fumes and figured if I was going to do this might try and do it some what right

I also found on the air filter snorkel door valve the nipple was large and the hose that fit that nippl was to loose on the Bi Metal valve on the filter floor. So I ran it to one of the valves (TVS) on the side as it has a large & small nipple. From the TVS to the Bi Metal switch then to the intake manifold.

None of the valves I used let air pass thru when I tried to blow thru them so how will the door close off cool air and open the warm air as the door is N.O. to cold air/N.C.to warm air. The temp in the garage was high 40's so I would think the valves would let air pass thru no?

Dave ----

 

[Gary Lewis]

What you are describing is the thermostatic vacuum bowl vent valve. This vacuum-controlled valve was used in 1984 and 1985 and replaced the earlier electric bowl vent solenoid valve for most models that used the small block Windsor engine.

One end (CARB) had a rubber hose that connected to the external bowl vent on the carburetor and the other had a rubber hose that connected to the canister purge valve. The canister purge valve connected to the vapor canister by a rubber hose. The vacuum port off the bottom of the thermostatic vacuum bowl vent valve connected to a manifold vacuum source. Anytime the engine is running manifold vacuum is produced and the valve closes, sealing off the external carburetor bowl vent. When the engine is off and manifold vacuum is no longer present, the valve opens back up to vent the fuel bowl to the charcoal canister.

Capiche?

Got it!

I plumbed this up this morning (2am could not sleep) and the way I did it was.

carb bowl vent> hose> valve with "carb" pointing to carb> hose to canister.

This hose stock had a "T" and based on the sticker on the radiator support went to the PCV upper nipple so that is how I ran it.

Now this valve with "carb" on it, I could not blow air thru it from either side so I took it apart. It looked clean inside so I put it back together and installed it.

So the way I see it with motor off no flow, you say it should?

I am not too worried on the carb side as it has a bowl vent under the filter assy. so fumes should stay there. The tanks go to the canisters and when the motor is running should get pulled in and burned.

Also because they are in a closed system I should not get any fumes from that when the motor is off either....I hope lol.

If you could not tell I did not want to smell gas fumes and figured if I was going to do this might try and do it some what right

I also found on the air filter snorkel door valve the nipple was large and the hose that fit that nippl was to loose on the Bi Metal valve on the filter floor. So I ran it to one of the valves (TVS) on the side as it has a large & small nipple. From the TVS to the Bi Metal switch then to the intake manifold.

None of the valves I used let air pass thru when I tried to blow thru them so how will the door close off cool air and open the warm air as the door is N.O. to cold air/N.C.to warm air. The temp in the garage was high 40's so I would think the valves would let air pass thru no?

Dave ----

Dave - On the air cleaner, I have the info on how the valves are supposed to work here: Fuel Systems/Air Cleaners.

[FuzzFace2]

Dave - On the air cleaner, I have the info on how the valves are supposed to work here: Fuel Systems/Air Cleaners.

That does help I think I have to switch the hoses on the Bi Metal switch but other wise I did it right.

I just cant see it working if I could not blow thru the switches........then again I may not of had enough hot air

I will have to check this when I get her running to see if it works as it should.

Any ideal how to do this? Cell phone set to record and placed so it can see the valve?

Dave ----

[LARIAT 85]

I plumbed this up this morning (2am could not sleep) and the way I did it was.

carb bowl vent> hose> valve with "carb" pointing to carb> hose to canister.

This hose stock had a "T" and based on the sticker on the radiator support went to the PCV upper nipple so that is how I ran it.

Yes, that is correct. The PCV valve is connected to manifold vacuum, and the top port will suck the fuel vapors trapped in the charcoal canister through the canister purge valve and into the intake manifold for burning.

Now this valve with "carb" on it, I could not blow air thru it from either side so I took it apart. It looked clean inside so I put it back together and installed it.

So the way I see it with motor off no flow, you say it should?

Yes, the thermostatic vacuum bowl vent valve (1984/1985) should be OPEN when the engine is off. (You should be able to blow through it.) The valve should close when manifold vacuum is present. This is the valve that whisler has.

Now, if you have an earlier thermal vent valve (1980 - 1982), it will be CLOSED when the temperature is cooler and open when temperature is warmer. This valve is green and yellow or white and black and is independent - it will not have any sort of vacuum control or electric control at all.

* 1980/1981:

A thermal vent valve is inserted in the fuel bowl vapor hose that opens when the temperature is warm. This provides a clear, open path for excessive fuel vapors from the fuel bowl to be routed away from the air cleaner and into the charcoal canister.

carb bowl vent> hose> thermal vent valve> hose to canister.

* If you still have the stock valve that came on your truck, this is what you have. Unless it is warm, you should NOT be able to blow air through it.

1982 - 1983:

Ford added an electric bowl vent solenoid in the fuel bowl vapor hose that is activated when the engine starts to block off the external bowl vent anytime the engine is running.

carb bowl vent> hose> thermal vent valve> hose> bowl vent solenoid> hose to canister.

1984 - 1986:

Ford combined the thermal vent valve and the bowl vent solenoid into one vacuum-operated device called a thermostatic vacuum bowl vent valve.

carb bowl vent> hose> thermostatic vacuum bowl vent valve> hose to canister.

I am not too worried on the carb side as it has a bowl vent under the filter assy. so fumes should stay there. The tanks go to the canisters and when the motor is running should get pulled in and burned.

Also because they are in a closed system I should not get any fumes from that when the motor is off either....I hope lol.

The external bowl vent is there to release excess fuel vapors and route them away from the air cleaner and into the charcoal canister. Without it, or if it is blocked off, the excessive fuel vapors generated from a hot engine that has been shut off will collect inside the air cleaner. This will create an overly rich mixture, and hard hot starts can occur.

Capiche?

 

[FuzzFace2]

I plumbed this up this morning (2am could not sleep) and the way I did it was.

carb bowl vent> hose> valve with "carb" pointing to carb> hose to canister.

This hose stock had a "T" and based on the sticker on the radiator support went to the PCV upper nipple so that is how I ran it.

Yes, that is correct. The PCV valve is connected to manifold vacuum, and the top port will suck the fuel vapors trapped in the charcoal canister through the canister purge valve and into the intake manifold for burning.

Now this valve with "carb" on it, I could not blow air thru it from either side so I took it apart. It looked clean inside so I put it back together and installed it.

So the way I see it with motor off no flow, you say it should?

Yes, the thermostatic vacuum bowl vent valve (1984/1985) should be OPEN when the engine is off. (You should be able to blow through it.) The valve should close when manifold vacuum is present. This is the valve that whisler has.

Now, if you have an earlier thermal vent valve (1980 - 1982), it will be CLOSED when the temperature is cooler and open when temperature is warmer. This valve is green and yellow or white and black and is independent - it will not have any sort of vacuum control or electric control at all.

* 1980/1981:

A thermal vent valve is inserted in the fuel bowl vapor hose that opens when the temperature is warm. This provides a clear, open path for excessive fuel vapors from the fuel bowl to be routed away from the air cleaner and into the charcoal canister.

carb bowl vent> hose> thermal vent valve> hose to canister.

* If you still have the stock valve that came on your truck, this is what you have. Unless it is warm, you should NOT be able to blow air through it.

1982 - 1983:

Ford added an electric bowl vent solenoid in the fuel bowl vapor hose that is activated when the engine starts to block off the external bowl vent anytime the engine is running.

carb bowl vent> hose> thermal vent valve> hose> bowl vent solenoid> hose to canister.

1984 - 1986:

Ford combined the thermal vent valve and the bowl vent solenoid into one vacuum-operated device called a thermostatic vacuum bowl vent valve.

carb bowl vent> hose> thermostatic vacuum bowl vent valve> hose to canister.

I am not too worried on the carb side as it has a bowl vent under the filter assy. so fumes should stay there. The tanks go to the canisters and when the motor is running should get pulled in and burned.

Also because they are in a closed system I should not get any fumes from that when the motor is off either....I hope lol.

The external bowl vent is there to release excess fuel vapors and route them away from the air cleaner and into the charcoal canister. Without it, or if it is blocked off, the excessive fuel vapors generated from a hot engine that has been shut off will collect inside the air cleaner. This will create an overly rich mixture, and hard hot starts can occur.

Capiche?

Well based on your post it may be the right TVV for the year truck as I could not blow thru it.

I am going to play it by ear and if I have a hard start hot issue I will look at this as a cause.

Thanks for the lesson

Dave ----

[rbond]

I plumbed this up this morning (2am could not sleep) and the way I did it was.

carb bowl vent> hose> valve with "carb" pointing to carb> hose to canister.

This hose stock had a "T" and based on the sticker on the radiator support went to the PCV upper nipple so that is how I ran it.

Yes, that is correct. The PCV valve is connected to manifold vacuum, and the top port will suck the fuel vapors trapped in the charcoal canister through the canister purge valve and into the intake manifold for burning.

Now this valve with "carb" on it, I could not blow air thru it from either side so I took it apart. It looked clean inside so I put it back together and installed it.

So the way I see it with motor off no flow, you say it should?

Yes, the thermostatic vacuum bowl vent valve (1984/1985) should be OPEN when the engine is off. (You should be able to blow through it.) The valve should close when manifold vacuum is present. This is the valve that whisler has.

Now, if you have an earlier thermal vent valve (1980 - 1982), it will be CLOSED when the temperature is cooler and open when temperature is warmer. This valve is green and yellow or white and black and is independent - it will not have any sort of vacuum control or electric control at all.

* 1980/1981:

A thermal vent valve is inserted in the fuel bowl vapor hose that opens when the temperature is warm. This provides a clear, open path for excessive fuel vapors from the fuel bowl to be routed away from the air cleaner and into the charcoal canister.

carb bowl vent> hose> thermal vent valve> hose to canister.

* If you still have the stock valve that came on your truck, this is what you have. Unless it is warm, you should NOT be able to blow air through it.

1982 - 1983:

Ford added an electric bowl vent solenoid in the fuel bowl vapor hose that is activated when the engine starts to block off the external bowl vent anytime the engine is running.

carb bowl vent> hose> thermal vent valve> hose> bowl vent solenoid> hose to canister.

1984 - 1986:

Ford combined the thermal vent valve and the bowl vent solenoid into one vacuum-operated device called a thermostatic vacuum bowl vent valve.

carb bowl vent> hose> thermostatic vacuum bowl vent valve> hose to canister.

I am not too worried on the carb side as it has a bowl vent under the filter assy. so fumes should stay there. The tanks go to the canisters and when the motor is running should get pulled in and burned.

Also because they are in a closed system I should not get any fumes from that when the motor is off either....I hope lol.

The external bowl vent is there to release excess fuel vapors and route them away from the air cleaner and into the charcoal canister. Without it, or if it is blocked off, the excessive fuel vapors generated from a hot engine that has been shut off will collect inside the air cleaner. This will create an overly rich mixture, and hard hot starts can occur.

Capiche?

Sorry to revive this older thread, but I'm at this exact stage on my project so I felt it appropriate to add to this existing thread rather than start a new one... "may as well have as much related info in one thread", I always say...

Lariat 85... your info re. how the system works was great... really informative, and it answered one of my more pressing questions... thanks much!

I'd like to add a few details to what has been said in this thread, so far... sorry in advance for the length of this post...

So... my '86 350 7.5L is a CA vehicle and has a twin set of vapor recovery system components:

2 carbon canisters

2 carb bowls

2 sets of TVV and SV CBV valves, with a pair of each running to each side of the carb.

This is consistent with my Vacuum diagram.

This might be a slight variation in components to what Lariat 85 was describing for '84 - '86 cars even though the functionality is the same. I don't have a single component thermostatic vacuum bowl vent valve, instead I have the 2 separate components that accomplish the same function. A TVV (Thermal Vent Valve) and a SV CBV (Carb Bowl Solenoid Vent Valve) ... they do different things, and based on the name, it's easy to figure that out, but they work in tandem.

It would seem that systems with the TVV, which looks like this:

 

are designed to only pass fuel vapor when atmospheric temperatures are warmer inside the engine compartment... around 140˚F and above (from what I have deduced from the spec in the Emissions Shop Manual) which means that these should be CLOSED at temps below that of the surface of Venus. Mine are not closed... but do pass vacuum at normal atmospheric temps. I'm currently looking for replacements, or trying to figure out if they are even necessary in my system. So far these little guys have been alluding me.

OR... am I trying to locate the single Thermostatic Vacuum Bowl Vent Valve component that Lariat 85 was referring to, to replace the 2 components I currently have?

Meanwhile, the SV CBV ... which looks like this:

is what allows vapor to NOT pass when the engine is running, as the solenoid is closed with ignition 12v.

One of mine works... the other does not.

I was stumped at first when testing these components (which should be done with low vacuum draws rather than simply passing air) as I had first found a similar component (CPRV) spec in the Emissions book that was described as Normally Closed:

... note the basic part number 9C915. In thinking this was my component, imagine my surprise when I found out that the units I have in my truck tested Normally Open...

... then, reading this thread, it jogged something in my brain and I came to realize that my part must be a different component... started digging and then found this in the Emissions Book:

... voilá... 9B982. The part I have.

So, NOW I have a question... Do I need 2 pairs of these components, one set for each Carb bowl... or can I simply T the 2 carb bowls together and feed them both with a common Solenoid and Thermal Valve combination? From the looks of my Vacuum diagram it would appear that they both function simultaneously anyway.

The next question is: WHERE DO I FIND THESE PARTS??? Or am I looking for a thermostatic vacuum bowl vent valve?

So far... my searches for any of these components has been fruitless.

[LARIAT 85]

Sorry to revive this older thread, but I'm at this exact stage on my project so I felt it appropriate to add to this existing thread rather than start a new one... "may as well have as much related info in one thread", I always say...

Lariat 85... your info re. how the system works was great... really informative, and it answered one of my more pressing questions... thanks much!

I'd like to add a few details to what has been said in this thread, so far... sorry in advance for the length of this post...

So... my '86 350 7.5L is a CA vehicle and has a twin set of vapor recovery system components:

2 carbon canisters

2 carb bowls

2 sets of TVV and SV CBV valves, with a pair of each running to each side of the carb.

This is consistent with my Vacuum diagram.

This might be a slight variation in components to what Lariat 85 was describing for '84 - '86 cars even though the functionality is the same. I don't have a single component thermostatic vacuum bowl vent valve, instead I have the 2 separate components that accomplish the same function. A TVV (Thermal Vent Valve) and a SV CBV (Carb Bowl Solenoid Vent Valve) ... they do different things, and based on the name, it's easy to figure that out, but they work in tandem.

It would seem that systems with the TVV, which looks like this:

 

are designed to only pass fuel vapor when atmospheric temperatures are warmer inside the engine compartment... around 140˚F and above (from what I have deduced from the spec in the Emissions Shop Manual) which means that these should be CLOSED at temps below that of the surface of Venus. Mine are not closed... but do pass vacuum at normal atmospheric temps. I'm currently looking for replacements, or trying to figure out if they are even necessary in my system. So far these little guys have been alluding me.

OR... am I trying to locate the single Thermostatic Vacuum Bowl Vent Valve component that Lariat 85 was referring to, to replace the 2 components I currently have?

Meanwhile, the SV CBV ... which looks like this:

is what allows vapor to NOT pass when the engine is running, as the solenoid is closed with ignition 12v.

One of mine works... the other does not.

I was stumped at first when testing these components (which should be done with low vacuum draws rather than simply passing air) as I had first found a similar component (CPRV) spec in the Emissions book that was described as Normally Closed:

... note the basic part number 9C915. In thinking this was my component, imagine my surprise when I found out that the units I have in my truck tested Normally Open...

... then, reading this thread, it jogged something in my brain and I came to realize that my part must be a different component... started digging and then found this in the Emissions Book:

... voilá... 9B982. The part I have.

So, NOW I have a question... Do I need 2 pairs of these components, one set for each Carb bowl... or can I simply T the 2 carb bowls together and feed them both with a common Solenoid and Thermal Valve combination? From the looks of my Vacuum diagram it would appear that they both function simultaneously anyway.

The next question is: WHERE DO I FIND THESE PARTS??? Or am I looking for a thermostatic vacuum bowl vent valve?

So far... my searches for any of these components has been fruitless.

Here is the later thermostatic vacuum bowl vent valve. This is what came on my [carbureted] 1985 F150 with a 5.0/302 engine. It works the same as the electric solenoid you have except closes with manifold vacuum. If you have two bowls, you will need two of these. I am not exactly sure why, but I have always heard you do not want to tee the fuel bowls together.

https://www.ebay.com/itm/OEM-Ford-E3TZ-9G332-A-Fuel-Charcoal-Vapor-Line-Shut-off-Valve-1983-1991-F150/232419408997?epid=1611254278&hash=item361d46bc65%3Ag%3AQvQAAOSwbApZcn7T&_sacat=0&_nkw=E3TZ9G332A&_from=R40&rt=nc&_trksid=m570.l1313

[Gary Lewis]

Sorry to revive this older thread, but I'm at this exact stage on my project so I felt it appropriate to add to this existing thread rather than start a new one... "may as well have as much related info in one thread", I always say...

Lariat 85... your info re. how the system works was great... really informative, and it answered one of my more pressing questions... thanks much!

I'd like to add a few details to what has been said in this thread, so far... sorry in advance for the length of this post...

So... my '86 350 7.5L is a CA vehicle and has a twin set of vapor recovery system components:

2 carbon canisters

2 carb bowls

2 sets of TVV and SV CBV valves, with a pair of each running to each side of the carb.

This is consistent with my Vacuum diagram.

This might be a slight variation in components to what Lariat 85 was describing for '84 - '86 cars even though the functionality is the same. I don't have a single component thermostatic vacuum bowl vent valve, instead I have the 2 separate components that accomplish the same function. A TVV (Thermal Vent Valve) and a SV CBV (Carb Bowl Solenoid Vent Valve) ... they do different things, and based on the name, it's easy to figure that out, but they work in tandem.

It would seem that systems with the TVV, which looks like this:

 

are designed to only pass fuel vapor when atmospheric temperatures are warmer inside the engine compartment... around 140˚F and above (from what I have deduced from the spec in the Emissions Shop Manual) which means that these should be CLOSED at temps below that of the surface of Venus. Mine are not closed... but do pass vacuum at normal atmospheric temps. I'm currently looking for replacements, or trying to figure out if they are even necessary in my system. So far these little guys have been alluding me.

OR... am I trying to locate the single Thermostatic Vacuum Bowl Vent Valve component that Lariat 85 was referring to, to replace the 2 components I currently have?

Meanwhile, the SV CBV ... which looks like this:

is what allows vapor to NOT pass when the engine is running, as the solenoid is closed with ignition 12v.

One of mine works... the other does not.

I was stumped at first when testing these components (which should be done with low vacuum draws rather than simply passing air) as I had first found a similar component (CPRV) spec in the Emissions book that was described as Normally Closed:

... note the basic part number 9C915. In thinking this was my component, imagine my surprise when I found out that the units I have in my truck tested Normally Open...

... then, reading this thread, it jogged something in my brain and I came to realize that my part must be a different component... started digging and then found this in the Emissions Book:

... voilá... 9B982. The part I have.

So, NOW I have a question... Do I need 2 pairs of these components, one set for each Carb bowl... or can I simply T the 2 carb bowls together and feed them both with a common Solenoid and Thermal Valve combination? From the looks of my Vacuum diagram it would appear that they both function simultaneously anyway.

The next question is: WHERE DO I FIND THESE PARTS??? Or am I looking for a thermostatic vacuum bowl vent valve?

So far... my searches for any of these components has been fruitless.

I like your thinking of placing all the info we know re this topic in one thread.

As for the using one of them in a T arrangement, I think the issue is the volume of vapor and, hence, the need for two charcoal canisters. Would you then feed the output of the one valve into both canisters? Other than the volume issue, I think it would work. But, do you need to pass inspections, and would they catch that?

As for finding the part, what you have in 9B982 is the core part number. To that you have to add a prefix and a suffix. Below is what the catalog shows for that part number, but it is VERY confusing. So, look yours over closely to see if you can find one of the numbers shown on the right side, like D8TE 9B982-B1A, which is the ID or engineering number. Those are frequently shown on the part - but that is not the part number.

Also, the CX-239 number is the Motorcraft number, and that's likely the number you need to order one.