rusted fuel line 1986 C20

[Artie in Miami]

The fuel filter kept getting clogged with rust...so...I dropped the tank. After almost 35 years, tank was in perfect shape. Rust was coming from 3/8" fuel line and sending unit 3/8" tube. This truck has 3 lines from tank that go to engine area...I know the 3/8' fuel line needs to be replaced...and probably the 1/4" return line from fuel pump...what about the 5/16" line that goes to the charcoal can...since that just deals with fumes, I am thinking that I can leave that and not replace. Is my thinking correct ? Strange that the tank did not rust, yet the fuel lines are full of rust. I am sure the humidity here in Miami had everything to do with that...probably got condensation in the tank over the years and ended up in the lines. I am replacing the tank anyway and the sending unit.