2000 LeSabre smells of gas after fill up

My LeSabre smells of gas when I fill up until the tank gets to about 1/2 - 3/4 full, then the smell goes away.

Any thoughts. Thanks

just does it when you fill iot uo huh? well first thing i'd look at is the neck to the gas tank. if not that may have a hole way up in tank. but it should be missing because it's sucking air if in tank. also you may have to drop tank if it's leaking at the fuel pump but check your gas filter to.

There are several places for leaks.

One can be the connectors at the fuel lines on the injectors on the motor. Open the hood to see if the smell is stronger.

Another is the lines from the tank to the fuel filter; earlier Buicks had a metal line and those corroded from salt early. Crawl under car to look. Note drops of fuel on ground with car idling.

Another factor is the access to the fuel pump and lines is inside the trunk. There's a round access cover screwed down. That should be sealed. Take floor mat out of trunk to find the opening; it's near the back seat.

And the gas cap may not be sealing with its rubber o-ring. See if inside of tank opening is covered with a brown gritty material. Clean off. Put petroleum jelly on o-ring to increase seal. Notice if the gas filler opening has a smell of fuel after driving with a full tank.

Beyond that you're into checking the special tubes and valves that vent the fumes from the tank through the carbon cannister. It's under the car.