Fuel pump humming

So I just happened to be in the garage, when I hear this humming sound. Tripped out for 10 minutes before I located it to the truck bed, then under the truck, and my fuel pump was humming. It was loud enough to vibrate the bedside. Like, made so much noise I thought a one of my drills was on in the bed. Now, a fuel pump relay from my memory is more like a buzzing sound. I started the truck and it went away.

Anyone have a pump fail yet? Were there symptoms? Last pumps I've had fail were my chevy (and it had no symptoms just shut off driving) and my camry (similar situation as with the chevy). But I've never heard of it switching on with no key. Any insight?

Truck had been parked for about 5hrs

 

Anyone?

 

its not the fuel pump, it is a vacuum pump drawing a vacuum on the tank and fuel system. perfectly normal operation.

 

Yea finally.found a thread regarding it. Freaked me out I had no idea it could run automatically

 

Evap system I am guessing.

 

I thought it would be under the hood for some reason. Glad it's normal at the 5 hr mark too. Just a coincidence I happened to be there when it goes off

 

Yeah, it freaks out those who sleep in the bed of truck in the middle of the night

 

Good point. Even stranger that I've never noticed it. Guess I'm in a different state of mind when in sleeping in the bed