[Wayne 962]

There is a solenoid that is activated in the engine compartment for a vent line to the tank / carbon canister. I'm not sure if a failure of this component would cause this noise, but it seems like it would be a likely culprit. The valve is electronically controlled and basically connects the tank to the intake manifold and pulls a vacuum on it when the engine is running. I'm not sure when this valve opens though. I think this and the fuel tank pressure sensor are the only two electronic components associated with the system?

-Wayne