A Tale of Two Fuel Tanks...it's a tankless job

msgjd said:

But seriously yes mister engineer i believe you are on target

Click to expand...

Guess that degree in Marine Biology finally paid off...

Just checked the Manual Fig. 46 TM 9-2320-260-20P lists the assembly as "vent". Parts list doesn't get into a lot of detail of the "whatsit", looks like the pipe bushing fits into it, but it's not shown.

The whatsit appears to be a pressure regulator. The top part vents freely to atmosphere. I filled the lower part with penetrating oil and charged the vent lines to 15 psi. Observed air fizzing through the oil.
See attached video


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So this isn't a static situation and the length of tubing does reflect the pressure of the tank.