Fuel Tank Evaporation Question

[Gregski]

Hi all, I have a '74 GMC 350 manual 1/2 ton 2WD, but I figure I pop in here and ask you kind folks some questions about the gas tank evap line and charcoal canister (if you even know what I am talking about, LOL) as I am not sure your trucks had these, that's what I want to ask you.

So how many lines run from your gas tanks to the engine bay? See mine has two one is for gasoline the other for fumes.

Do you guys have a charcoal canister in your generation trucks in the engine bay?

I am asking cause I want to delete the charcoal canister from my engine bay giving it a nicer cleaner look, and I was thinking maybe I go back to the way my trucks daddy was set up, and so I am asking how things were back in 1967 to 1972.

FYI I did find some of the old shop manuals and I am thumbing through them as well, but it don't hurt to ask, you know what I mean

[Gregski]

from the Manuals I gather that in 1968 there were no fuel tanks with emission systems (first pic)

I am missing the '69 shop manual, but in 1970 (second pic) there is now a Fuel Tank with evaporative emission control

interesting...

[Don Quixote]

I am in the process of converting my gas tank to EEG in one way, shape or form. The EPA keeps changing the standard for vented gas caps and I must have bought about 4 of them thinking they were all defective before learning this. I had to drive from Arizona to Tennessee while reaching out the window to burp the gas tank every few miles which became a pain in the a$$. I am; however, more concerned for function as opposed to aesthetics.

There are a few who simply run a breather valve on the tank and those who will run a vapor line to the air filter from the tank. I am not 100% sure how I want to proceed. I may actually pick up a canister at the pick apart and mount it to the frame rail to save space in the engine compartment. We don't have as much room as you do in the squares.

...a little food for thought.

[joeydurango]

EEC became standard midway through the 67-72 model years, if I'm not mistaken. I believe the change wasn't across all versions at once, though. I have a 72 truck with a 70 cab and tank, and my truck doesn't have the EEC components any longer. I'm simply running an old-school vented cap (not the new "vented" ones, they are NOT the same). I've heard of people using the canister, and also not using the canister and simply venting the canister line along the frame (making sure to keep the "high loop" from the tank intact). But don't just seal everything up unless you're positive you have a truly vented cap, or you'll have problems.

[cdowns]

I always just discarded the cannisters while using the tubing to it as a vent for the tank
they ran great no problems at all for over 30 years

[MARKDTN]

I would just leave it.

[Bigdav160]

The canister is hidden behind the right fender so I haven't considered removing it for aesthetics.

[Gregski]

Originally Posted by cdowns

I always just discarded the cannisters while using the tubing to it as a vent for the tank
they ran great no problems at all for over 30 years

That's what I am thinking of doing, but do you run your hoses to the engine bay or nix them somewhere under the truck?

[cdowns]

Originally Posted by gregski

that's what i am thinking of doing, but do you run your hoses to the engine bay or nix them somewhere under the truck?

i always just ran them to a spot alitte bit away from the tank where it was not noticable