Thanks all. Lots of good info.
Mine is an electric fuel pump about two feet from the tank way in back so I don't think heat is the problem here. Restriction is the most likely problem. I'll bet the pump is cavitating because the filter is too restrictive.
It also occurred to me that the only time I have this issue is when the fuel level is low. The pump is mounted at about the mid level of the fuel tank. So when it has too suck through that filter (which has a years worth of gunk in it), up hill and in warm temps. it's just too much.
The fix is clear. Thanks again.
