Rubber hoses at the top run to steel. They could be leaking there as well.
The reason that the steel line is used is for safety. It won't melt through like rubber and is stronger and less likely to be damaged if something from the road hits it.
Can you use rubber? You could. Just make sure it is a high-pressure fuel line. They also make special band clamps for high-pressure connections.
IF you are unable to see the leak via the ports, then I honestly recommend removing the tank. If you lower it slightly, you may see the leak but may not be able to repair it.
Also, I made a copy of your first picture and circled a component. I'm having trouble orienting myself. If you look at pic 2, can you identify which part I circled? I don't like the looks of that. It looks like either a tracking arm or a control arm. Make sure the rust isn't
to a point it's weak.
Let me know what I can do to help.
Images (Click to enlarge)
Monday, April 26th, 2021 AT 7:37 PM