Since I bought my '93 I had trouble filling the tank. I could never use any of the big rig pumps and the little auto pump would foam badly even if I only partially cracked the valve.

Tonight I took my filler neck apart and figured out why. The factory foll over valve ball was only the beginning of the problem. When I got it out of the way, here are some pics of what I found.

The melted plastic had constricted the neck to about the size of a quarter. No stinking wonder I couldn't fill up my tank worth a darn. Gotta fill it up in the morning and I'm anxious to see if that truly solved my problem.

 

I think Id be kinda concerned as to how it melted...

 

I thought about that too, but everything that I saw indicated the problem arose when the plastic was cast into the metal neck. It looked to me like it was still molten when they removed the casting and/or there was excess plastic in the mold. Also, there was no discoloration or melting on the metal and/or rubber boots.

Besides, there is no heat source near the valve location so I can't imagine how that happened after the fact.