79 KZ400 Cafe

I understand what you are saying, but it's pretty clearly not flowing from the petcock. It's not like the line is full, it's just not flowing. The fuel line itself is full at first, but then it goes to completely empty. Just a light drizzle flowing through it.

Rusty tank? While as assistant mechanic at a motorcycle shop that was the case more times than not. Especially on old beasts. Relining them is as easy as it sounds. My tank was re-lined while I was working there. We used a KREEM kit. It cost's about $80.00 but gives it a beautifully sealed new lease on life. Its takes about two days to complete the whole process.