Guys, what’s on right now? My truck is off

Hey guys,
So every now and then my truck (2018 trd sport 4dr) a humming sound in the gas tank area on underside of the truck. Ive only noticed it when it’s completely silent. This has only been noticed when I’m in the garage working. It just starts up and runs for...I don’t know, it’s been on for about 5 min now and still is. The truck is completely off. No key even near it. It sounds like the fuel pump circulating the fuel. What’s going on here?

 

No worries, it’s normal. Even says so in the owners manual.

 

Yes. Normal. My subi does it too

 

Thanks

 

Does anyone know what this is?
Our Sienna used to do it... but only for 3-4 seconds at a time. (5 minutes would start to concern me...)
I never worried about it - but I have no idea what that was.

 

It’s a fuel Evap leak test the truck performs.

 

Mind blowing how many people here actually read the owners manual...

 

You’ll actually be surprised how many cool little features there are or stuff you thought you knew.
I started reading it when I couldn’t figure out how to turn off traction control completely lol(you have to hold it for 8 seconds if you didn’t know).

 

Oh I definitely should, just something I never even thought about doing in all my years of driving a car. I think the only time I’ve ever looked at one was to figure out a replacement bulb....

 

That's not it.

 

Depending on when certain criteria are met, (ambient air, time since engine off, etc) the truck will pull a vacuum on the gas tank to detect any EVAP leaks. The humming u hear is the little vacuum pump by the tank.

 

Comes from working in high tech industries for over 40 years. Glad to be retired now!