Hi all!

I have the strangest query... my Accord (99,1.8 LS,auto) is making a faint, intermittent buzzing noise hours after being driven and parked up. It seems to be coming from the underside of the passenger rear side... I'm baffled... maybe some fuel system de-pressurising or something. The noise happens maybe every minute or two for acouple of seconds each time - its not always the same, and thoug hvery faint, sounds like 'hhmmm hhmm hmmm!!!'.

It almost sounds like a fuel pump noise, but how could this be running (even briefly) with the car off hours and the ignition off and keys out...?

Any thoughts...?

 

It is probably something with the evap system. There is a valve that opens when the fuel pressure reaches a certain pressure and the vapors are trapped in the charcoal canister.

You are probably hearing the valve open. I am not sure how it is supposed to operate when the car is shut off though.

 

You in UK? Passenger side = left side?

There's a valve that lets fuel vapor out through the charcoal canister (underneath the left-rear seat). It's like a check-valve to prevent air getting INTO the fuel tank, but some of them are a bit more noisy than others. You're not the first to describe a buzzing sound, but when I had a 1998 mine was barely audible "sshh" sound. I could only hear it if I closed the garage door & listened real carefully.