van hums randomly when warm

[phychotron]

I get a strange hum from my fuel system when its warm. Its comes from the front top of the gas tank, and will stop if I vent the gas cap. It happens randomly, in the morning before I drive it sometimes but usually monetarily after I park. The fuel pump jumper isnt jumped.

No smell of fuel even when I was under there investigating.

https://youtu.be/k1LIfgiTKtE

[Burntboot]

It's been my experience that when fuel pumps start to be heard in abnormal ways, its just their way saying "please replace me, before I leave you stranded"

[MarkH]

Vacuum in the tank leading to air being drawn in past the loose gasket on top of the tank where the fuel pump goes in? Sort of like blowing up a balloon and stretching out the neck and letting the air scream out.

[Burntboot]

It sounds like an over worked or tired pump.
When was the last time the fuel filter was replaced?

We used to have a Jag that would make a similar sound.
Rust residue in the tank would slowly fill up the filter until the pump would have a hard time pushing against the restriction.
That resonant hum became the early warning indicator for filter replacement as tanks were NLA.
For what its worth, that noise would occur long before it became noticeable, from a drivability perspective.

If the filter isn't "new" it might be worth replacing it as a first step.
I would also be tempted to cut it open, to see what clues it may provide.