Weird tapping noise on 2016, long after shut off

Purchased my second 4runner last July, 2016, SR5 and I have ongoing issue with a noise. I go out into my garage and this happens hours since I've shut the engine off I hear a tapping noise. Tonight I just opened one of the doors to see if I could hear it better and then it stopped. But I have heard this before, I thought it was my hot water heater in the garage, but it is the car. It is a very faint tapping noise underneath the car and I had parked it about 6 hours prior, thanks for any ideas

 

Other forums have found that it is part of the EVAP system for removing fumes from the gas tank. It usually occurs after shut down and is nothing to worry about.

 

freaked me out the first time I heard it too.

 

Thanks very much, I will ignore it then

 

Really annoying when you are sleeping in the 4runner. Discovered it this weekend when on a camping trip. Goes on 5 hours after shut off and continues for about 10 + minutes. Started the engine and it didn't go back on during the night.

 

You may have a gremlin in there

 

this is part of the fuel evap leak check program ... after the vehicle sits for several hours the PCM does the LEAK test ... this does not do anything but check for a leak in the fuel vapor system....
possible it could be programmed to do the check much sooner ..

 

Always wondered about that noise. Both 15 and 17 4Runners did it, so figuared it was normal. Thanks for the update.

 

IT doesn't remove gas vapors from gas tank LOL.....very odd ...

 

Any Idea what the noise is?

 

this is part of the fuel evap leak check program ... after the vehicle sits for several hours the PCM does the LEAK test ... this does not do anything but check for a leak in the fuel vapor system....
possible it could be programmed to do the check much sooner ..

just saying there will always be gas vapors in the fuel tank !

Toyota does this when shutdown ..GM does this when vehicle is running .. in the fuel tank is a pressure sensor as vacuum is applied to the fuel vapor system the pressure sensor reports how the pressure/vacuum changes if its out of the programmed software parameters, then a code will throw..

 

Thank you for explaining.

 

Yay!!
The 4Runners forum made me look like a real smart feller. My wife heard this noise tonight, I heard it a couple of nights ago. I was able to tell her what this was.