Sound while truck is off (update: EVAP system self-test sounds)

[Deleted member 8188]

2025 Limited
7,700 miles
Non-Hybrid

Truck had been off for about 7 hours when I walked into the garage and heard this. It sounds either like a mini air compressor or a fuel pump to me.

Is my truck equipped with a self inflating spare or something? Is this just the fuel pump keeping pressure?

Definitely coming from under the bed

I don’t know how long it had been doing it. But when I turned the truck on and off it went away.

I’ve owned it for 7 months and it’s never done this. I live in AZ so I’m not in the cold spell of the rest of the US.

appreciate everyone’s help.

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[Deleted member 8188]

After googling some more I’m guessing it’s the evap self test? Never heard it before

If anyone can follow up and let me know they’ve heard this I appreciate it


Yes, the fuel pump in a Toyota Tacoma is designed to run periodically while the truck is off
as part of a normal, automated evaporative emissions (EVAP) system self-test. This is a standard function, not a malfunction.

Normal Operation

• Purpose: The EVAP system performs a pressure test hours after the engine is shut off to check for fuel evaporation leaks.
• Timing: This self-test typically occurs about five hours after the engine is turned off and may run for a minute or two.
• Sound: The test involves the EVAP pump (often mistaken for the main fuel pump) making a humming or buzzing noise from under the vehicle, near the fuel tank area.
• Interaction: The noise is normal and will stop if a door is opened or the ignition is turned on.
  

 

[tna]

Yes it’s the EVAP system checking for leaks. Completely normal. I freaked out one night when I went to throw the trash and heard it. Had to Google it too.

I have my grille lights tied to the same fuse so every time the EVAP check kicks on….so do my grill lights.

 

[Yotota]

The owners manual has a section about this.

It's the EVAP system self-check.

 

[LincolnSixAlpha]

So I've been wondering what it was. Usually occurs around 8 or 9pm I've noticed, after the truck has been parked for many hours. Was making me nuts there for a while, then I finally gave up and didn't care anymore. But glad to know what it is now.

 

[Pappy]

This happened to me awhile back in the boonies of AZ. I have an engineer-type buddy that works for Toyota. I sent him a text about this. His answer ...

"Evap emission pump. Running a self check. If no check engine lights then no worries."

 

[Sner]

The owners manual has a section about this.

It's the EVAP system self-check.

boggles me how many people ask about this, yet Toyota puts a note about it in bold within the first 10 pages of the owners manual.

 

[LincolnSixAlpha]

boggles me how many people ask about this, yet Toyota puts a note about it in bold within the first 10 pages of the owners manual.

When I was a younger man I poured over owners manuals, loved every minute of it. Now I find that the little glossy pamphlet they give you is good enough for me these days, but your point is valid.

 

[Sner]

When I was a younger man I poured over owners manuals, loved every minute of it. Now I find that the little glossy pamphlet they give you is good enough for me these days, but your point is valid.

Okay, I hear you. I’m an instruction manual / owners manual reader. What you’re saying is better than not reading anything, here’s my next argument, second biggest purchase you make in your lifetime next to a home and you can’t even read the first 10 pages of its owners manual?

 

[maxx075]

Okay, I hear you. I’m an instruction manual / owners manual reader. What you’re saying is better than not reading anything, here’s my next argument, second biggest purchase you make in your lifetime next to a home and you can’t even read the first 10 pages of its owners manual?

Why would I do that when I can come onto a forum where people have probably already had this issue, solved it, and made multiple threads on it - but instead of searching for things like that, I instead make another post so that it goes to the top of the queue. That way it gets immediate attention and responses. Genius really.

 

[Sner]

Why would I do that when I can come onto a forum where people have probably already had this issue, solved it, and made multiple threads on it - but instead of searching for things like that, I instead make another post so that it goes to the top of the queue. That way it gets immediate attention and responses. Genius really.

You call it genius - okay. I wouldn't call someone a genius who can not help themselves by doing a a search or doing some reading on their own to see if they can solve a problem. Would rather be spoon fed answers to their problems. Imagine the world we'd live in. Nikola Tesla, Albert Einstein, Issac Newton, they'd all be looking for answers from someone else.

 

[maxx075]

You call it genius - okay. I wouldn't call someone a genius who can not help themselves by doing a a search or doing some reading on their own to see if they can solve a problem. Would rather be spoon fed answers to their problems. Imagine the world we'd live in. Nikola Tesla, Albert Einstein, Issac Newton, they'd all be looking for answers from someone else.

Lol I forgot the emphasis of sarcasm there. I 100% agree with you and have said the same thing multiple times here.

 

[Sner]

Lol I forgot the emphasis of sarcasm there. I 100% agree with you and have said the same thing multiple times here.

Phew, the clarification helped. Wasn't sure how to take it, felt you were on the fence

 

[Deleted member 8188]

Why would I do that when I can come onto a forum where people have probably already had this issue, solved it, and made multiple threads on it - but instead of searching for things like that, I instead make another post so that it goes to the top of the queue. That way it gets immediate attention and responses. Genius really.

theres nothing in this forum about the evap self test. I tried to search for it myself.

Why would I do that when I can come onto a forum where people have probably already had this issue, solved it, and made multiple threads on it - but instead of searching for things like that, I instead make another post so that it goes to the top of the queue. That way it gets immediate attention and responses. Genius really.

there is nothing in this forum about the evap self-test. now there is a detailed post with a video. you're welcome.

 

[maxx075]

theres nothing in this forum about the evap self test. I tried to search for it myself.


there is nothing in this forum about the evap self-test. now there is a detailed post with a video. you're welcome.

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