Hum when truck is off

I know this will sound weird but I went into my garage to get something and I could hear a hum by the backside of the truck by the garage door. I walked around the truck from the drivers side to the passenger side to try and get an idea of where this noise was coming from, but it stopped when I was got close. The truck had been parked there for around 5 hrs. Any idea what this could be? Anyone else have this happen to them?

 

Thats interesting that you brought this up cause I think this also happened to me a couple months ago but I never looked into it but I could have sworn I heard a humming nose too? But I think mine started a few minutes after my truck was parked and not hours after.

 

Last thread on this claimed it was a fuel pump.

 

autobot?!

 

There is something in the manual that tells you what it is. IIRC, it is a purge valve for the tank. I'll look it up. It says something to the effect of, " after your truck has been off for approx X amount of minutes, you will hear ___________ coming from the rear"


errr somethin.

 

Sounds like I may not be going crazy after all! I did a search on here(TW) and could not find anything, though it does sound like I have another way to approach it with the fuel pump.

 

Yea. its the vapor pump. Bet your low on gas when it does this.
Happened to me the other day when I pulled in the garage and I heard thid "humm....hummmm.hummm.hummm" I was like "wtf".

 

Thanks guys! I wonder if the dealerships realize how much busier they would be if there were no Tacoma World, it is really nice to be able to ask a question on here and get the answer you need!

 

Thanks for the input Colton!!

 

Those that did the fog light mod in the early days knew about this because some of them wired the fog relay up to the power feed for the emission control which runs what you were hearing. So their fogs would come on every 5 hours while the truck was off for 30 seconds to a minute. I've never heard the one on my Taco run, but the one on our '10 Highlander can be heard easily in the garage. Funny story from a Highlander forum in that a guy in Canada recently bought a HL that was a US model and they had to modify the lighting (something to do with the DRL requirements being diff in Canada). Anyway, the dealership wired his DRL up to the emission control power feed. He was home and discovered his headlights coming on after 5 hours. So I filled him in on what was happening. Second dealership had to remove all the "wrong" wiring and fix it.

 

I didn't know that (but then I never wired my fogs to the wrong lead before).

 

I made a post about this the other day. It sure sounded like it was the fuel pump running on mine. It was down just below 1/4 tank and it had been sitting about 5 hours. Kind of freaked me out. Oddly enough in the 5 years I had my 4 cylinder 05 tacoma I never heard this. I was very glad to hear it was normal though. I've been wrenching on the daily drivers way too much this winter. Funny how nothing on them ever breaks when I have my 2 extra "toy" vehicles to drive in the summer months.

 

5 hours is what it was, from my original post. My wife had parked the truck in the garage at about 5:30 and I had went out in the garage at 10:30 and heard the noise, it's all starting to make sense. Thanks again!