2018 TRD fuel pump (I think?) running 5 hours after engine off

Hey All,
Has anyone heard their fuel pump running several hours after the engine was stopped? My truck was parked about 5PM last evening. At 10, my wife called me out to listen to a strange noise coming from the left rear wheel well. The "whirring" noise sounded like a electric motor and my brief history replacing the fuel pump on my Dodge Dakota many years ago almost convinced me it was the fuel pump. As I touched the Engine Start Button the whirring stopped just before the engine started. I kept in running for 2 minutes, shut off the truck, and did not hear it again. Each time I check today I hear no noise so I can't duplicate the event, but I also don't know if it occurred before and I just could not hear the whirring due to background noise.
I was able to discuss this with my dealer's service guy today but he was not convinced it was the fuel pump, instead telling me it could have been a sensor that was doing a self check. Not knowing that much about the 2018 electronics I was not going to disagree with him but I did tell him about my prior experiences and the fact that it sounded "like a motor", not a sensor noise location was "really close " to the fuel tank.
So asking the question again; Have you heard your fuel pump running long after the engine stops? Other than battery drain (probably more than a day to do that) what else bad would happen beside the pump wearing out?
Thanks in advance for your replies.
Marc
(PS. I hope I can figure out all of the "tech" features of my '18 before I get too old to drive it)

2010 SR5 2WD Access Cab, Barcelona Red (RIP! 11.30.17)
2010 SR5 4WD Double Cab, Barcelona Red (Wife's truck)
2013 SR5 4WD Access Cab, Barcelona Red (My "Woods and Waters" truck)
2018 TRD Sport Double Cab/Long Bed, Inferno (My retirement truck, 2 years early, Commute to work truck.)
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High pressure pump is ran off the engine though isn't it?
My best guess would be it was running a leak test, pretty common it runs after a couple hours being shutoff

 

That is correct. the camshaft is the HPFP's pump.

 

It's an emissions related device that does random checks. Forgot the name, it's in the owners manual and is harmless.

 

This, it is simply running a test, it is right there in the Owners Manual.

 

You’re right, just woke up and wasn’t thinking

 

It is normal. I've caught it a number of times so far in my garage and at work. Always a number of hours after shut down.

 

Tell her its your Brojoe maker you set early for your morning commute and its just grinding the beans early to let them breathe a bit.

 

Hey Guys,
Thanks very much for the replies and the reassurance. Shakerhood or Specter208 , Can you please cite which page or where I should look in the manual? Is it under Emiisions, Random Checks, ?
Thanks again for the replies.
Marc

 

I have not been in the Manual for awhile, it is definitely in there though, the same system was also in the 2nd Gens Tacoma's too.

 

Scared the shit outta my wife when she was in the garage.

 

My cat decided to take a snooze under my old Tacoma when it went off, she came flying out from there, lol.

 

Page 8 - download the PDF manual, makes keeping it in the truck a lot easier and you can read it at work.

https://www.toyota.com/t3Portal/document/om-s/OM04017U/pdf/OM04017U.pdf

 

Hey OnHartung's Road,
Thanks for the link to the manual and it's right there on page 8. Five hours after engine is off, and that's when I heard it. The link is appreciated,
Marc

 

So happy I found this thread. I'd occasionally hear what sounded like a tiny air compressor running under the bed of my 2016 TRD Sport and couldn't figure out how to describe it to my more mechanically savvy friends. Glad to know it's nothing weird.

 

Wow I love the interwebs! Just heard this sound and ten minutes later I know not to worry. Would never have thought of looking at the owner’s manual...what a concept.

 

I agree with johnbets, a quick search and answer is a big time saver! If only I had read my manual to page 8