Weird knocking noise underneath after refueling

Hi All,

Something strange is going on. It literally sounds like somebody knocking on wood and just happened for the first time after refueling. It's most prominent in the video around 0:34 and for the last few seconds at the end.

Any ideas? Does anybody else's do this?

https://youtu.be/Q9XuHBC2ea4

 

This must be stumping everybody. One commenter on my video said his Corolla made the same sound and it was the fuel pump. Still hoping for some feedback here.

 

Did you pack the tank or stop on the first click off when full?

 

Here is what google mechanic says.

A thumping noise in the gas tank after filling up a Fourth generation Tacoma is likely due to the fuel tank's pressure regulating system, which is designed to vent excess pressure. This system may release trapped air after filling up, creating a noise. It's generally considered normal and a safety feature. However, if the noise persists or is accompanied by other issues, like a malfunctioning fuel pump, it's worth investigating by a qualified mechanic, especially one familiar with Toyota vehicles.

 

Solution:

Stop fueling when the pump first clicks off.

 

Stopped after the first click. I never go beyond that because I know it can cause various issues.

 

This is interesting. If that's AI, I'd take it with a grain of salt, but it does make sense.

 

With this being a new generation Tacoma and not much known I would stop by your dealership service department and lay the question on them.

If they don’t know the answer they will make up some BS that sounds good that will ease your mind.

 

Was hoping to avoid a trip to the dealer at least until my first service. I did not hear it on my drive today so I will keep an eye on it, especially after I refuel again.

I have a feeling this will pop up again on this forum with other people, normal or otherwise.

 

You can try giving them a call….

 

Vapor recovery system? I hear occasional noises in the rear when the truck is parked in a quiet garage. Those sounds are the vapor recovery system. They sound more like high frequency pump vibrations to me than a thumping sound, but it could be the same system. The sound was more pronounced on my 2021, but I still hear it operating on a 2024.

 

Is it continuos? Take gas cap off and put it back on

 

Interesting theory about the vapor recovery system. Does it sound like what's in my video?

Not continuous, very sporadic. Easiest to hear around 0:34 and toward the end of my video

 

General update: I have driven it several times since refueling and it has not made the same sound at all. It was only the one drive after the refueling, then not again on multiple drives after that.

 

Yes, I think it does. Less thumping more tapping. I thought the vapor recovery system operated when the vehicle was idle not running. This makes the sound very audible if you are listening for it. I really do not know, just interested in what the sound could be… can the VRS run when the vehicle is running?

 

For those (few) of you interested in this, it's doing it again after a fresh refuel and I captured the sound much better in this video. Feedback appreciated.

https://youtu.be/ZVp-jF6xClw

 

Personally, I have never heard this sound in my 2024.
Hearing it (again) in a better recording it does not sound like the vapor recovery pump or system.
Hopefully you can get a Toyota tech to hear it during a service visit.

 

Yeah, I am thinking I need to schedule something, then fill it up right before driving to the dealer so they can hear it real time.

 

Have someone from the dealership ride with you to fill it up.

 

Are you sure that sound is not coming through the exhaust?