Tank vent routing stepside

[dhenderz]

Where does the fuel tank vent route on a stepside? On my 77 K10 the vent was plugged by the PO so I have no idea where it is supposed to go. I assume somewhere up high within the fenders. Or was there a charcoal vacuum canister in the engine bay by 77? Again, the PO had removed all of the emission equip so nothing is left as a reference.

 

[75gmck25]

On my '75 the steel vent line runs up the passenger side frame rail (it might be driver's side on your '77) to a point very close to the fuel pump. From there they have a rubber line that runs over to the bottom of the vapor canister, which is on the driver's side next to the lower side of the radiator. My truck originally had a vent line running from the canister over to a fitting on the Quadrajet, but my newer Quadrajet (one from about 1980) did not have that fitting for the vapor line, and I left it just hanging for a while.

You can see the vapor canister on the left side of this picture. I had the vent line that originally ran to the carburetor disconnected, and later just connected it to a fitting I added to the air cleaner. I figure that will draw enough air to pull vapor out of the canister. If there was ever a check valve or solenoid in my system to control the vapor purge, there is no evidence of how it worked.

Bruce

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