Vacuum on fuel tank

[RonNBama]

A few months ago I had a strange problem with the diesel tank on my '98 Dynasty. I noticed that the filler cap had a significant vacuum on it when I went to fuel up. This started happening after I had replaced the cap gaskets to stop fuel running out when completely filled. I finally traced the multitude of lines coming out of the tank and found the vent hose. Turns out it had been converted to housing by this critter:

It's big at each end,
little in the middle.
It digs up dirt,
and goes like a fiddle.

Pesky darned insects! :-)

[RonNBama]

A few months ago I had a strange problem with the diesel tank on my '98 Dynasty. I noticed that the filler cap had a significant vacuum on it when I went to fuel up. This started happening after I had replaced the cap gaskets to stop fuel running out when completely filled. I finally traced the multitude of lines coming out of the tank and found the vent hose. Turns out it had been converted to housing by this critter:

It's big at each end,
little in the middle.
It digs up dirt,
and goes like a fiddle.

Pesky darned insects! :-)

[RV Wizard]

Sounds like a mud dobber get him!

[RonNBama]

Should have been my very first guess but I was focused on making the problem as difficult as humanly possible. :-)