Dual tank upgrade

[saltershawn74]

I have a 78 K20 project truck that I want to put dual tanks from my parts truck on. My project truck only has a 3/8 fuel line but the parts truck has a return and vent line as well. Do I need the return and vent line?

 

[75gmck25]

It depends on the fuel pump and sending units, and the tank venting. - - Return lines and 3 port fuel pumps and sending units were added by GM in later years because they help cool the fuel in hot weather and prevent vapor lock. The fuel returning to the tank cools down instead of just dead-heading at the pump, where it is close to the exhaust manifold heat.
- The vent line and vapor canister were added when they stopped using vented gas caps. The vapor line and canister should prevent any fuel smell from coming into the cab.

 

[saltershawn74]

So I should replace the fuel pump with one that has a return line port and adding a canister for a vent. Where does the venting canister typically go?

 

[scrap--metal]

Where does the venting canister typically go?

The vapor canister is typically mounted on the driver's side of the engine compartment. In front of the wheel well and behind the core support.