I made a "Gush Protector"

If gas is pumped into the tank too fast it can gush up the filler neck and the spilled gas ruins the paint below the fill hole. I made a spout to convey the spilled gas away from the car and over the bumper.

I cut the corner out of a one gallon plastic milk jug and made a spout to fit below the fill hole. The curvature of the corner forms a channelized spout.

Attachment 2948

The spout snaps in place and the top is cut in a curve to fit around the fill hole. The screw threads fit against the top edge of the bumper and create a small tension against the fill hole edge to hold the spout in place.

Attachment 2949

You may also want to disconnect the vent line on the tank and put compressed air through it. So many have found that tube to have critters (50 years worth) taking residence in this tube and it is clogged up. If the tank can't vent while you fill, it will be worse.

Also, many of those here with cars have used mid-60's F-100 truck fillers and relocated the filler to the trunk. Seems to fill, they say, better with a vertical fill neck.