did you ever
Did you ever get to look at a good check valve. do you think the white thing, is the flag showing its bad. I'm thinking it is . I have ordered a new filter housing if it dose turn out that the white thing is not showing I'll post .HERE Is a thread where a guy with a 2006 had a fuel filter problem and HERE is his first thread about the same problem.
It turns out a check valve in the filter head failed, blocking fuel flow through the filter.
This is what the failed part looks like:
You can see a white thing in there just to the left of center. This is the check valve that failed. I'm trying to get a picture of an unfailed one as well as more information on this.