72 k10 fuel tank question
 

Is this a condensing loop for fuel vapors? It comes from the engine bay
And is unhooked at the engine end...truck has a 350 with a quadrajet 4 barrel.
I am doing a 6.0 LS swap soon and need a return line to the tank...

Re: 72 k10 fuel tank question
 

It is part of the EEC system. Emissions control. That smaller line goes up into the rear corner of the cab and then down to the frame. From there is goes forward to a charcoal canister up front then back to the carb.
Does the gas tank sending unit have one outlet on it or two? If it has two the 3/8 line is engine supply and the 1/4 is a return line from the fuel pump.

Re: 72 k10 fuel tank question
 

No charcoal canister on this truck. End of hose in engine bay is loose. The sending unit on tank has one line, but there is a second line to the corner of the tank on the passenger side (just out of the picture)