Just found this today. Any ideas as to why this could be happening? I'm guessing only solution is to replace the tank. Makes sense as to why I am having so many problems with filling the tank and why I have a smaller capacity.
Maybe it's vacuum and not pressure you're hearing.Weather has Been low 40's high 30's lately so should be no ice. Yes I do hear pressure released when you loosen the fuel cap. Wasn't sure if that was normal or not. Looks like ill be dropping the tank to check the lines. Any way to get the tank back to normal after unclogging the line if that happens to be the culprit?
The TDI's have no EVAP system like gassers and are vented to atmosphere by a vent separate from the cap.Clogged tank vent is my vote.
I would think the weight of the fuel in the tank would "push" it back out if you could sort out the venting issue.Let's see, maybe either the vent in the cap is bad or the filler neck. As for the tank, instead of replacing it, try removing the pump and see if you can push the tank bottom back out.
I would agree. The fuel weighs a bit and after time the tank will relax under the weight and "deform" back to orginal shape. Particularly once we get back into summer temps.I would think the weight of the fuel in the tank would "push" it back out if you could sort out the venting issue.