I've noticed that in the heat of the day, when I shut the car off, sometimes the fuel pump continues to run. Sometimes the fuel pump will even start back up after I shut the car off. It only happens when it's really warm out 95+, with the AC on, and doesn't stay on long either like maybe 2 minutes, it's as if it's running to cool down the pump or something. I noticed that when I changed the pump there seems to be some type of sensor on the fuel pump module. So there's a wire for the fuel sending unit, wires for the fuel pump and then one wire that runs to this round silver thing (could that be a pressure sensor or temp sensor) for the tank? I'm aware that depending on the coolant temp, the speed of the fuel pump is adjusted also ( i.e. coolant temp below 32 degrees signals high speed operation) Just wondering if the opposite were true....Just wondering if anyone knew! Thanks in advance!

I have not heard of this. You are sure the fuel pump is actually coming on, vs. something else you might be hearing?
If it really is the pump running with the key off, I'd start with the green relay on the right side between the trunk finisher and the wing (quarter panel)-- sort of by the aerial.

I sure will check next time it happens. I'll unplug the relay and see if it stops. Like I said it only happens when it's really hot outside and I'm assuming higher vehicle temps.

I had an epiphany in the night.
Disregard the relay theory for now.
It's your gas cap (99%). When warm the vapors in your tank expand and push the relief valve in your gas cap, causing a high frequency vibration that is audible.
You can verify this by slightly loosening cap when you hear the noise (I'll venture that you also get a nice "whoosh" sound when you remove the cap to fuel up.....)

I have always gotten the release sound when fueling up in warm weather. I know that's normal but what you're saying is that the cap vents fuel vapor to the atmosphere when too much pressure builds up? I wasn't aware of that so it's a pressure cap much like a radiator cap huh. I'll give it a try thanks!

There is a check valve near the right rear wheel that I think you're hearing. It's supposed to bleed excess pressure off to the carbon canister in the front near the air filter box. I've heard it too, and thought the same thing. If you loosen the gas cap you may feel air pushing out instead of the usual air sucking in to the tank.