Hi all,

I have a replacement evap canister from Barrett that has been int he car for a year now. Lately, when the engine is heated up (about a half-hour of driving), I can hear a loud howling or humming coming from the evap canister. What would cause this? I've checked the valve coming from the valve cover and it is clear. I don't believe I have any leaks as I have tested the cars' pollution control system for leaks.

A mystery that needs to be resolved. It's embarrassing sitting at a stoplight sounding like a bagpipe! LOL

 

There are three moving parts that can go wrong under the hood with the vapor recovery system, (1) the canister intake vacuum valve, (2) the canister outlet valve, and (3) the evap canister solenoid (which controls the canister outlet valve). It's usually caused by building up too much pressure in the system. One quick test would be to let the car run until it starts making the noise. Loosen the gas cap and see if it stops. If it does, it's usually one of the three.