Every 5 or 7 minutes, from underneath the car when its off, it makes a buzzing/whining noise as if the fuel pump is priming or something. I'm not so sure it is because its not similar to the sound the car makes as soon as I switch it on before starting. Is there anything hooked up that periodically turns on and off when the car is off?

2000 Si btw... stock

 

my car does that too, and no one has ever been able to figure it out

 

Maybe the ECU rent-a-cop doing it's nightly patrol of sensors and all other thingamabobs?

 

It's air pressure releasing from the gas tank. All my hondas did it. Open the gas cap when it makes the noise and it will stop.

 

i thought it was the fuel pump like priming

 

my 97 integ does that too and so does my 98 accord v6. think it could be sensors chekin or fuel pump. it does it all the time but once i heard it on most hondas i didnt mind it