I was informed by a mechanic that they need to take the gas tank out to replace my fuel lines in my 1999 Honda Civic and also need to replace the brake lines because they run parallel. I am not sure if this is correct.

 

this is true. gotta drop the tank to get to the lines that run to top of tank. as for brake lines all depends on what spots, but im sure dropping tank out will add more access...again if that's the area to replace.

 

Yes I'm going through this with my 94. Once you touch the clips holding the fuel and brake lines under the car, the brake lines are almost certain to fall apart too, so the mechanic is not putting you on saying he needs to replace everything. There is a fuel line, fuel return line, tank vapor line, and two brake lines.

New lines for the 94 are no longer sold by Honda, so I'm fabricating new ones from scratch from CuNiFe tubing (one trade name is "NiCop"). This costs more than steel tubing but it is easier to work with and does not rust.

It is a major job. Many cars have been written off when the lines underneath rust out.