[Mgs] Fuel device identification?

[Keith G.]

I was messing around under the hood of my '79 B last evening and 
found an unrelated problem:  With just the fuel pressure of having 
the ignition turned on for a few moments I found a minor fuel leak.

The leak is coming from an object just past the fuel filter.  It's a 
small gray cannister thingy, with some kind of spring-loaded push-
button-like contraption on top.  The fuel goes into one side of the 
cannister and out the other.  (Interestingly, I noticed the word 
"INLET" under the what is currently the outlet side.)  It's held in 
place by a ring on the shelf of the firewall -- not tightly, but just 
snugly enough that it can be inserted into and removed from the ring 
by hand.

What is this device?  I need to to know what to call this thing in
order to buy a new one.  A look-over of the Haynes manual's diagrams 
did not help,  but maybe I missed it.

-- 
Keith G.
1979 B