Noise from under bed when off?

So I'm in the garage late at night having a smoke, and all of a sudden I hear a noise come on. It's like a mechanical hum sound and it's around your average TV volume. It was coming from under the bed. I couldn't tell exactly where, but once I stuck my head under there, I also heard what sounded like air or liquid traveling through a pipe also under the bed. My truck was off for a few hours, and I wasn't even near it. Is this normal? It's a 2015 Tacoma and I bought 3 months ago with 99 miles on it.

 

Your truck is just purring with delight.

 

RTFM.

 

I've had this happen once on my 2015. I went outside one night to grab something out of the bed, heard a humming sound coming from under the bed. Further investigation found it to be coming from the fuel tank, right in the middle on the bottom, I could feel the vibrations. I assumed it was the fuel pump.

The keys weren't even in the truck.

I went and got the keys, cycled the ignition, and the noise went away. Hasn't happened since. Well, not that I've noticed.

 

Hmm, never heard of it until now.

Good to know, thanks.

 

Happens 5 hours after you drive it, actually. Every time.

 

Tacorgasm.

 

No kidding, really? What does it do, just pressurize the fuel system and check for leak down?

 

60% of the time, every time!

 

@BamaToy1997

https://www.tacomaworld.com/threads/toyota-tacoma-evap-system-testing.263128/

 

Runnnnn!!!!!


I recently replaced my evap canister. Cost me about $300. If it doesn't pass that "test" you will get a cel.

 

Tire psi auto adjust....... thaats why it happens when its been off for awhile.

 

Knew about this but never caught it until today when the wife got home and said there was a buzzing in the garage. Around 5 hours after I last ran the truck.
Question: How long does the test take? Went out 15 minutes later and all was quiet.

 

it varies from a split second to id say 45 seconds for me

 

It was on for a few minutes and I came back 15 later and it was off. Not seconds in my case.

 

The fuel EVAP system runs a fuel tank and vapor system diagnostic test when all of the parameters are met. Typically the truck needs to be run for a "cold start" test. This means that the engine coolant temp must be below a certain amount, and then the vehicle driven for a minimum amount of time/miles. Shortly after you shut the truck off, it measures pressure decay in the tank and evap system to determine if there is a leak. Then if the vehicle has sat for the required time period, which is around 4 or 5 hours for Toyota, it will cycle the fuel pump and run additional evap tests. These tests are required to check for any leaks that could allow fuel vapors to vent into the atmosphere.