Could be the fuel pump "main relay" they get old and the solder inside becomes brittle and cracked. Then when they get hot the heat expansion is enough to allow cause an open, thus not allowing current flow. No current flow through this relay means your electric fuel pump will not turn on. Anyway, sometimes when the relays are starting to go, these symptoms will occur but if you wait a few minutes, the relay will cool off and contract then it will work again. If this is more of a problem in warm weather, it may just be it. Hope this helps.