Always wanted to ask does anyone elses fuel pump run while the car's parked? Every 8-10 minutes SOMETHING will hum for 5 seconds. Closest I can narrow it down is the fuel tank. Been that way for years now the hum pitch has changed. 2001 Accord v-6 92,000 miles.

 

as soon as the key is in the ignition and turned acc the pump starts running......

if when not without the key, could it be a fan ?

 

Probably the EVAP canister venting the gas tank.

 

Yeah, the 6th-gen EVAP canister is under the car, below the left-rear seat. As gasoline evaporates from the tank, it vents thru that charcoal canister. There's a relief valve that opens occasionally. Some cars that happens to be louder for some reason. The 1998 that I had, you had to really listen for it in a quiet garage. Never actually noticed the sound out in the real world.

 

Exactly! If I working in the garage w/o radio that dang thing will hum evry 10 minutes. My wife thought I was nuts till I made her sit there long enough. And you say it will continually pugre fumes?

 

As gasoline evaporates, the gas tank can only hold so much pressure, so it has to be vented. EVERY car has some similar system for this. The EPA says this evaporation is an unburned hydrocarbon emmission, so it has to be trapped as much as practical. That's the job of the EVAP system by venting that through a canister of activated charcoal.