[fredjacksonsan]

That's really weird. I've never heard of just melting the cap and rotor. I'd say since he's run out of gas twice and it happened twice, there's probably some sort of correlation. So tell him to fill up at 1/4 tank.

If he fills up at 1/4 tank and it happens again,then there's another problem. But if it doesn't happen again, you will have figured it out - don't run out of gas.