What causes a gush of air when the gas cap is removed on a 1992 accord lx the gas cap has been changed so its not the breather valve and notice the rpms jump up on highway unless the cap is loose?

Answer 1

I think most cars have a "breather" line that goes to the engine compartment to a canister. this let air into gas tank withour letting gas vapors into the air. In the old days the gas cap had a small hole to let air in, but now that we watch the environment this is the way it is done i think. check the line and the canister, i think sometimes it gets swamped with gas or otherwise clogged, so when you drive the gas going to the engine creates a vacuum in the gas tank due to not being able to suck in any air to replace the used gas in the tank. I think most cars have a "breather" line that goes to the engine compartment to a canister. this let air into gas tank withour letting gas vapors into the air. In the old days the gas cap had a small hole to let air in, but now that we watch the environment this is the way it is done i think. check the line and the canister, i think sometimes it gets swamped with gas or otherwise clogged, so when you drive the gas going to the engine creates a vacuum in the gas tank due to not being able to suck in any air to replace the used gas in the tank.