Ditto on the work, the great photos, and even finding that patent paper for more background.
Seeing four "devices" inside the tank. The orange fuel filler tube (with the spring-loaded flap at the end!), and the black,Tubular, Vent valve with a smaller and a larger hose going out of the tank. Noted that the filler tube is pointed toward the right side, i.e., where the fuel pump is located and appears to be supported by a metal brace. In this regard, is that orange fill tube just press-fit onto the metal tube going out of the tank, or is the black ring some sort of retainer?
Then there's two other devices, one orange at the filler end of the tank, and a lighter, yellow device at the front. There's a metal tube from the yellow device to a "T" in a hose going from the orange device to an external nipple. Each seems to have a spring-loaded float to close an opening at the top. The nipple that these are connected to, I believe, goes to the Shut Valve, the device at the top of the fuel fill tube that switches when the fuel filler nozzle is inserted. Both these devices appear to provide venting from the tank via the Shut Valve, but would not be related to a filling problem because the Shut Valve is supposed to be closed when filling. (Unless there's some additional plumbing we can't see in the photos.)
So the problem of filling the tank, where the tubing to the canister has been disconnected, could be with the Vent Valve, or, perhaps, now that it's apparent, that spring-loaded flap at the end of the fill tube (e.g., not opening enough to allow full flow of fuel into the tank).
In regard to the Vent Valve, if air is blown into the large hose that goes to the canister (as was done in the related thread -- https://www.subaruoutback.org/forums...ing-issue.html
), that air should go into the tank and come out the fill tube (gas cap off). The hose and diaphragm valve both appear to have similar diameters, so there should be fairly free flow in this case (inhibited only by the diaphragm spring that tends to close the diaphragm valve).
As discussed in the related thread, if the Vent Valve float sticks in the up/closed position, that would block the path between the tank and the diaphragm, preventing air from going out. But if air is blown back into the canister tube, and it comes out the fuel fill tube, that should mean there's an open the path from the tank, at least until the next time the fuel level in the tank again raises the float to the closed position. (I believe the spring associated with the float in the Vent Valve photos is positioned to hold the float in the open/down position, thereby ensuring a normally open path except when the fuel level is very high. @aero901
, is that correct?)
For the Vent Valve to work properly when filling, pressure builds up inside the tank, and that causes the diaphragm to lift away from the Valve opening (seen in photo #37), providing a path for vapor to the canister tube. The diaphragm has to be intact for the tank pressure to cause it to lift. @aero901
; if you blow lightly into the atmospheric fitting on the valve (the smaller one), can you tell if diaphragm is intact? I'm wondering if in @STepeci
's case, the diaphragm is broken, so that pressure in the tank doesn't cause it to lift.
(Related: aero901's original thread with photos and diagram: https://www.subaruoutback.org/forums...ml#post5827689
But again, that was some fantastic work and a very significant contribution to the overall knowledge base of this forum. Very much appreciated!