Are you referring to the charcoal canister? That scavenges fumes from the gas tank and converts them back to liquid gasoline, then that gets sucked up into the engine through the purge valve. A clogged charcoal canister will cause a "whoosh" when you open the fuel cap.
Did you replace the external fuel filter when you replaced the pump? A fuel filter should be purchased at the same time as the pump even if it's been recently replaced in order to honor any warranty.
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Originally Posted by the user formerly known as ZX3_Chick
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