I’m hoping I can gain permission to post a thread about this buzzing issue I’m having. Seems like the sound is coming from the EVAP canister apparatus, but I need to get some more information.
The next picture shows a hose which by disconnecting, completely eliminates the noise.

If I let my engine run for a few minutes and shut it off, pressure gets built up again enough for the buzzing to continue.

The buzzing continues even after months of having kept it in storage with the battery disconnected.

I just noticed today that by disconnecting the specific hose, the buzzing goes away.

What do I need to replace?
What are the causes of this?
How much will replacement of appropriate parts cost?

Here’s a brief YT video I made demonstrating the issue

This is not unusual for the vapor canister to release pressure/make noise after engine shutoff. This is fairly well documented amongst the 3rd gen 4Runners.

I would not be overly alarmed, as long as your emissions seem normal, meaning they test within reasonable limits and so on.

The video was helpful, I could not tell that your engine was running, so all seems normal.

If this noise were to be constant -for example with the engine running, then you may have cause for concern.

96Red did the same though different sound after 200k mi or so never an issue for 174k mi - wreck totaled - crusher, ha.

I have a buzzing while getting driving and intermittently.. read somewhere it's the brake booster.. could this be it?

No, in 01 it was moved to rear above spare tire. What you have is the stability control buzzer going off, system needs calibration. Read up on it.

I thought the ABS pumps did a self test once they reached a certain speed each start up. Maybe he is hearing that? Only happens once per trip though.

Misinterpreted the post, brain fart.
Yes pump motor running makes a noise.

01 and 02 are both back near spare tire. I didn't know if it switched in 1999 or 2000.

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Evap canister are under the hood on my 2000's

The later model (but pre 01/02) evap canisters had a slightly redesigned section right there to eliminate the buzzing sound. It is/was some sort of resonance in the canister and doesn't affect function. I think there is even a TSB about it if you search.

-Charlie

That answers that question. all under hood till 2000 then moved to spare tire 2001 and 2002..:-)

More info: 4runner-evapbuzz - bugeyebug

-Charlie

Too bad the the part needed to fix the buzzing is no longer available. My 96 does same thing, kind of annoying.