"PaulH" wrote in message
om...
There can be plenty of reasons for this besides pilot error. A while
back one of my fuel drains developed a slow leak, and there are
probably a dozen other possibilities.

that is pilot error. You should be able to find that leak - 100LL leaves
stains. If it was so slow not to notice, then it should be slow enough not
to matter in a flight. There are few fuel problems that are not pilot
error.