What's Evaporative Emission Control?

[71CHEVYSHORTBED402]

Shows as E.E.C. in the parts book. Is it the vapor canister, vented cap, smog pump, other?

Thank you

[LongBox]

The vapour canister, fuel tank cap with proper vent valve, various rubber hoses, and a connection to the intake, possibly through a valve.

Supposed to capture evaporation from the tank and the carb, and route the fumes into the intake to be burned in the engine, thus saving us from a catastrophic collapse of the earth's atmospheric ecosystem....

[Boog]

Yes. All those fumes that would vent to the outside without the EEC system. What are you looking at in the catalog? Gas tanks? Engine vacume draws fumes from the tank through a vent line up to the charcoal canister then into the engine to burn rather than let them vent to the outside.
LMC catalog has a good blow up of the tank and lines.

[71CHEVYSHORTBED402]

Originally Posted by Boog

Yes. All those fumes that would vent to the outside without the EEC system. What are you looking at in the catalog? Gas tanks? Engine vacume draws fumes from the tank through a vent line up to the charcoal canister then into the engine to burn rather than let them vent to the outside.
LMC catalog has a good blow up of the tank and lines.

Thanks for the responses. Shame LMC and everyone else doesn't sell a repro. canister. Someone could make a lot of money. I have two OEM, so okay, but the bottom rubber foam element wear out in these canisters.

I see EEC in the parts book on occasion, and the subject came up for a non-EEC gas cap.

Speak of gas caps, I haven't been successful with the following question. Do you use a vented cap with a functional vapor canister system? Also, I've read a post where the guy claimed some cap vents are one way. I believe he eluded to air entry, not vapor release. Thoughts?

I'd like to get the right cap to use with the canister. Thanks for any input.

[Mike_The_Grad]

I think 70-72 were the only years that the EEC tanks were used. I have a 72 c10 with 350/th350. Because I don't have to smog my truck I removed everything I thought at the time was related to it.( I was only 18) that included the evap canister,and associated vacuum lines. I still had the hard steel evap line connected to the tank, but it was just open to atmosphere in the engine bay close to where the fuel lines connect to the mechanical fuel pump. But I still had the original non-locking gas cap. Which is vented. But it's considered to be vacuum vented. Meaning it allows air in while the fuel is drawn out but the fuel pump. If there is any positive pressure build up in the tank, then that is where the evap canister comes in to the equation. The evap canister stores the excess fuel fumes while the engine is not running and releases them when the engine is running in order to be drawn into the intake/carb.
Anyways, I wrecked the truck back in 2004 and it sat for about 8 years. It only ran a few times in those years until I could finally invest some time and money. Well the original gas caps rubber seal was shot,which allowed water to get into my tank each time it rained. So I got a chrome Stant locking gas cap, pulled the tank from the cab cleaned it out real well, which surprisingly was in near perfect shape on the inside. Replaced the sending unit, which for the correct setup has two outlets: 3/8" main fuel supply and a 1/4" fuel return line from mechanical pump.
The vent line that would normally go to the vapor can is actually ran along the frame rails parallel to the fuel lines, enters the cab at the same place as the fuel lines, but splits off along the bottom edge of the fuel tank towards the passenger side rear cab support pillar up the inside of the pillar and loops back down to the top passenger side of the fuel tank where it enters the tank and runs along the inside top to about the middle of the tank.
Takes longer to type and read than to visualize.lol.
So I eliminated the vapor line that ran along the frame rail and basically have my tank vented to atmosphere below my cab. With mine setup this way it doesn't matter if I ran a vented gas cap or not because there is always a "vent" to atmosphere. But if you retain all the components of your system,(which I recommend) then you want a vacuum pressure vented gas cap.

[iriereggaeman]

Originally Posted by Mike_The_Grad

I think 70-72 were the only years that the EEC tanks were used. I have a 72 c10 with 350/th350. Because I don't have to smog my truck I removed everything I thought at the time was related to it.( I was only 18) that included the evap canister,and associated vacuum lines. I still had the hard steel evap line connected to the tank, but it was just open to atmosphere in the engine bay close to where the fuel lines connect to the mechanical fuel pump. But I still had the original non-locking gas cap. Which is vented. But it's considered to be vacuum vented. Meaning it allows air in while the fuel is drawn out but the fuel pump. If there is any positive pressure build up in the tank, then that is where the evap canister comes in to the equation. The evap canister stores the excess fuel fumes while the engine is not running and releases them when the engine is running in order to be drawn into the intake/carb.
Anyways, I wrecked the truck back in 2004 and it sat for about 8 years. It only ran a few times in those years until I could finally invest some time and money. Well the original gas caps rubber seal was shot,which allowed water to get into my tank each time it rained. So I got a chrome Stant locking gas cap, pulled the tank from the cab cleaned it out real well, which surprisingly was in near perfect shape on the inside. Replaced the sending unit, which for the correct setup has two outlets: 3/8" main fuel supply and a 1/4" fuel return line from mechanical pump.
The vent line that would normally go to the vapor can is actually ran along the frame rails parallel to the fuel lines, enters the cab at the same place as the fuel lines, but splits off along the bottom edge of the fuel tank towards the passenger side rear cab support pillar up the inside of the pillar and loops back down to the top passenger side of the fuel tank where it enters the tank and runs along the inside top to about the middle of the tank.
Takes longer to type and read than to visualize.lol.
So I eliminated the vapor line that ran along the frame rail and basically have my tank vented to atmosphere below my cab. With mine setup this way it doesn't matter if I ran a vented gas cap or not because there is always a "vent" to atmosphere. But if you retain all the components of your system,(which I recommend) then you want a vacuum pressure vented gas cap.

Hi Mike_The_Grad - would you be able to tell if I have an EEC tank based on the photos here: http://67-72chevytrucks.com/vboard/s...d.php?t=683634 - IrieReggaeMan post from today.

Thanks!

[Steeveedee]

If you have 3 lines to your tank, it has the EEC system. Also, you can buy a new vapor canister filter at any parts store. This says for Firebird, but they are all the same.

http://www.partsgeek.com/x1893mf-pon...FUlNfgodrw8FFQ

[iriereggaeman]

Originally Posted by Steeveedee

If you have 3 lines to your tank, it has the EEC system. Also, you can buy a new vapor canister filter at any parts store. This says for Firebird, but they are all the same.

http://www.partsgeek.com/x1893mf-pon...FUlNfgodrw8FFQ

Thanks Steeveedee!

[In The Ten Ring]

I have pics of my EEC system but I can't get photobucket to work for me.

I plan to hook mine back up as close to OEM as possible, I guess I'll have to get a charcoal canister from a donor vehicle.

*The same tech is still used on modern cars. My 2002 Honda Accord's canister needed replacement last year, the first time the "check engine" light came on in 15 years.

[71CHEVYSHORTBED402]

I don't know man, this EEC system business freaks me out.

First off, I found my 71 like this image. There's one line at the sender & one line that I believe was run to the vapor canister, factory. Thing is, I believe the original fuel pump had just one port connected to the tank. In other terms, the system didn't have a return line.

The current fuel pump does have two ports. One uses the vapor line as a return, the other feeds the gas. The vapor can was pulled, so a vented cap is required. I'd like to reconnect to factory, but can't seem to get confirmation for what I think is the factory configuration, consistent with this image, a vapor line connected to the canister, and a fuel pump with a single port (i.e., no return line).

Then there's my 72. It has two lines at the sender. Both go to the fuel pump. I'm assuming it had a vapor canister, but all evidence is removed.



My 71

[chestypuller]

you should see this contrapton on my 71 blazer in the back its a tube with 3 hoses going in it, took that sucker out, gonna cap the line from the tank.

[Mike_The_Grad]

[QUOTE=71CHEVYSHORTBED402;7934660]I don't know man, this EEC system business freaks me out.

First off, I found my 71 like this image. There's one line at the sender & one line that I believe was run to the vapor canister, factory. Thing is, I believe the original fuel pump had just one port connected to the tank. In other terms, the system didn't have a return line.

The current fuel pump does have two ports. One uses the vapor line as a return, the other feeds the gas. The vapor can was pulled, so a vented cap is required. I'd like to reconnect to factory, but can't seem to get confirmation for what I think is the factory configuration, consistent with this image, a vapor line connected to the canister, and a fuel pump with a single port (i.e., no return line).

Then there's my 72. It has two lines at the sender. Both go to the fuel pump. I'm assuming it had a vapor canister, but all evidence is removed.

You would be correct in your assumption. That line was to the vapor canister originally. Which also means your sending unit has be replaced at some point in time. But as you can see your truck is probably running jist fine with it setup the way you have it.