Question, do they have a life? Bulkhead nut is tight. Washers appear to have no cracks . Filled tank and can see fluid still dripping from bulkhead . Thoughts, comments , suggestions. Thanks

Mike, over time, they do harden and deteriorate. When you replace them, be sure to buy the correct size. That is, a #10 washer for a #10 fitting; the fitting has a register that the washer sits on.

I use a thin metal shim and an o-ring on both sides on my fuel tanks.

As posted above, the O ring washers are a good option. I think Magnafuel has those.