1952 Mercury fuel tank

[Gronk]

I have a 1952 Mercury 4dr Custom. I recently went through the fuel system from the carb back .She runs fine. When I removed the sending unit to peer into the tank as best I could with a lite all seems well . I noticed a tube in there that runs from the top of the tank, (best I could tell) to the drivers side where it exits and then runs up the inside of the rear fender and down again into the fuel tank . Does anybody know what this is for?  It doesn't show or mention it in the manuel. Thanks in advance 

[JACK M]

Vent tube of some sort?

[Gronk]

I now think you are probably right. Although the gas cap is vented.

[m-mman]

It is the vent to allow filling. As you pump gas in quickly it allows the air to escape. Something that is forbidden in the evaporative emission containment world of the 21st century but didn't matter back in 1952. 

And it would also vent the tank as you draw from it. 

[19tom40]

The Chassis Parts Catalog shows that the 52 Mercury required a non-vented cap. The short filler pipe required a different venting system than the side mounted filler pipe to prevent spilling of the fuel while driving..

 

There is a picture of the fuel system on page 192 of the 49-53 Mercury parts catalog that shows the vent hose going from the tank to the filler pipe via a pipe in the fender. The P/N are MA-9107 and MA-9108.

[Gronk]

Thanks for the info guys!