What is this?

[gmcbuffalo]

Here is a photo of the fuel fill tube and the tank air vent. Anyone have a idea what the brass fitting with the plastic blue cap. Under the cap is a tread and a small hole. OOps I took the blue cap off in this picture.

[LNDYCHT]

It is the low pressure valve for the fuel tank. I believe that even with a cap it would vent enough around the threads.

[dreamchasers]

It is the low pressure valve for the fuel tank. I believe that even with a cap it would vent enough around the threads.

Lee, I'm impressed!!

Hector

[gmcbuffalo]

So what you are saying is that since the fuel cap is a non vented cap this fitting allows air to enter the tank to replace the fuel that is used.
Greg

[LNDYCHT]

There are two pressure relief valves one low pressure located at the filler and one high pressure located at the tank. I believe that both of these are check valves and only allow air in. Expansion is handled by the air space at the top of the tank, that is why they warn not to overfill the fuel tank.