Many amateur and professional plumbers may be familiar with the Flowmaster (Quick Install) 400A Fill Valve which is like an all-in-one, once and done fill valve sold at Walmart and all hardware stores. It is very common and easy to use, but!
Like everything, they changed it for the worse. Before I even start, I notice a white plastic piece just inside the mouth of the gray intake tube (about 1-in up inside) where the supply line connects to the intake tube. This white piece blocks like 99% of the intake tube. The instructions say nothing about it (of course).
What is this? Should it come out? Can I take it out? It’s not made for easy access, but one could jam a scratch awl or a screwdriver in there and clear most of it out. Why do companies do such stupid things? (Aside: Honda put a small, plastic filter (like the shape of a target) just inside the mouth of where the oil goes. It blocks the use of a funnel. I could break it, but the shrapnel would drop deep down into the tube to who knows where. 
I’'ve had four of these vehicles…I know it’s there just to piss me off.)