Sound From Truck Hours After Shutdown

Went into the garage hours after parking the truck and heard a strange noise that sounded like something was running. Got under the truck and it appeared to be a black box next to my fuel tank / spare tire.

After I shot the video I wiggled all the connections and it ended up stopping. Just a little concerned as my 2014 only has 5k miles on it.

Anyone ever had this happen and what the hell is it?

Here is a photo and video of the area and the noise.



Video to follow once photo bucket approves it....

 

I think it's probably your fuel pump. They have some new EPA stuff on those new Tacos and for some reason the pump goes on and off every 3-4 hours.

Maybe someone else can explain why? I have an 07 so none of that "intelligence" in mine.

 

Normal. I have a 2013 and it does this once in a while. There's a couple threads on it. I caught mine veryearly in the morning like 8 hrs after shut down. My co worker has a 2014 and his does this also.

 

its an emissions thing...........completely normal.

shit, us with blowers have the superchargers intercooler pump cycle as well

 

Thanks everyone for the replies. Just have never had that happen before on any vehicle.

 

I hear ya with that mine has scared the shit out of me a couple of times

 

my dad heard it the other day as I was gunna leave and asked if it was my fuel pump. The truck JUST started the noise/check as I opened the door.

 

It is the evap system running its checks which is usually five hours after shutdown all normal

 

I've heard my 2014 do it a couple of times. Unnerving at first.

 

mine is going this - tonight i opened the fuel cap and let off the pressure and it stopped instantly.

it seams to be related to when i fill up and put in an extra couple of gallons of fuel - so maybe it's the evap or fuel pump trying relieve pressure from overfilling??

what ever the reason it's nuts for something like a fuel pump to run with the ignition switch off.

 

I believe it is a vacuum pump pulling the vapors out of the tank and capturing it in a charcoal canister. First time I heard mine do it I was car camping after a long drive into the Sierras and thought something was wrong with the truck. I've car camped several times since and it always turns on a few hours after I've parked, waking me up and running for several minutes.

 

no answer and i think i will keep my nuts and stay away from the prius - the post after your's gives the best guess

 

answer - http://www.motor.com/article.asp?article_ID=1072

The key-off vacuum pump design is Toyota 's latest evaporative emissions system. As its name suggests, it has a vacuum pump that automatically leak-checks the evap system after the vehicle has been shut off. A typical key-off charcoal canister and vacuum pump assembly is shown in photo 1 below. The pump unit or pump module is on the right side of the canister. The key-off evap system first appeared on 2004 Highlanders equipped with 2.4L 4-cylinder engines. Then Toyota gradually expanded its usage throughout the 2005-06 models; by now the majority of its products use it.
This key-off design has much in common with the nonintrusive and intrusive systems I covered earlier this year in Foreign Service. But there are four major differences between those systems and the key-off setup. First, as I just mentioned, the key-off system performs a leak check when the ignition switch is off. Second, a small vacuum pump creates the vacuum for this leak check. Third, the so-called back door of the key-off system is configured differently than the one on earlier evap systems. Finally, a Toyota-friendly scan tool is more important than ever for diagnosing the evap system quickly and accurately.
I'll cover the main features of the key-off evap system monitor now; we'll peek at the parts and component operation a little later. By now, many M otor readers have experienced the aggravation of coaxing some vehicles to complete an evap monitor. Everything from engine temperature and fuel slosh inside the tank to weather conditions and local traffic can complicate this task. The thing you'll like about Toyota 's key-off system is that it eliminates the worst aspects of common evap monitors. For instance, the typical enabling criteria for a key-off system leak check are:
the engine has been shut off for five hours;
the ignition switch is off;
engine coolant is 40° to 95°F;
intake air is 40° to 95°F;
altitude is less than 8000 ft.;
battery voltage is 10.50 volts or greater.
So for most readers in most areas, the vehicle has already run the leak-check part of the evap monitor as long as it has sat for five hours and the battery hasn't gone dead for some reason. Depending on fuel tank size and fuel level, the vacuum pump usually runs 5 to 10 minutes or less during this test. (Later, when we have to replace batteries in these vehicles, this will be another argument for installing a high-quality battery with the proper electrical capacity!) And yes, the driver can hear the vacuum pump running.
Toyota has taken two steps to tell the customer that pump operation�and therefore pump noise�is normal. First, it hangs a warning tag on the shift lever (although no one can be sure how many of the warning tags survive the predelivery vehicle inspection). Also, a notice is printed in the owner's manual (that old-fashioned, print-media object hidden inside the glove box).
If the coolant and air temperatures cited earlier aren't within the specified range, the ECM will wait an hour and then attempt a second leak check. It can make several attempts at one-hour intervals before aborting the test. The ECM also aborts the leak check if the vacuum pump can't stabilize evap system pressure within approximately 12 minutes.

 

Holy novel Batman , it was answered in post #9

 

i was looking for more info... the guessing is about how / what the test is doing

as far nuts go - u brought up the topic - from what i understand nuts is a big part of owning a prius - u must hang them from the rearview mirror while driving...