Then I may not be in my right mind; although I'm NOT recommending patching, I've found that on a couple of 240s I've owned, the line from the tank unit to the main pump has rusted quite badly where the clips secure it to the body, and where it bends and follows the body up toward the top of the tank. It seems to be quite localized and cleaning the gunk off the line I found it was still shiny except in a couple spots. I'm sure it's a bad idea but I've cut out the rotten section & bent up a new piece of copper line that I've secured to the original line with proper fuel hose & clamps. It works in a pinch (in fact for a couple years on one car). It's steel line originally, by the way. Copper doesn't rust through, but it does have less abrasion resistance and strength than steel - along with a lower melting point and higher price - good reasons for a safety-conscious manufacturer to use steel instead.
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Chris, Dartmouth NS Canada 70 M-B 280SE, 83 245DL, 84 244 turbo, 90 780 turbo, 92 VW Golf, 90 740 Rex/Regina