The MYSTERIOUS Fuel Filter Tube

Some of you may have run into this tube while replacing your fuel filter. It would seem that this tube was present in the original, factory installed filter. It's function is debated, but here is my main theory.

When you remove the fuel filter (after appropriately relieving fuel pressure), you will still have fuel in the lines and in the filter. If you have this tube installed, it will help prevent fuel from spilling out when you remove the fuel hose on the OUTLET side. Unless there is fuel high enough to be above the hole in the tube (inside the filter), the fuel will be sealed in there. Then you can get a catch can/cup ready and slowly remove the tube to catch the fuel.

Some have argued it might be some sort of restrictor, but removed or not, my fuel pressure was exactly the same. I guess it's possible that not as much fuel would be delivered to the rail if there is a restriction in the line, but I think this tube would make a negligible difference.

So, remove it, leave it there. It doesn't seem to matter, but it's good to know other owners have wondered the same.