M1008 Fuel tank 'drain' tube? What about a fuel tank air pressure bleeder?

[Carl1008]

There are three tubes on the M1008 fuel sender: Fuel out to the engine (duh), fuel return (semi-duh), and the mysterious 'drain' (huh).

What's the drain for? How does it work? It's just a short tube that goes a few inches and then terminates with a 'CAP' as per the TM -20P. (Section II, Figure 17, Part 30)

But, when I removed the sender, I noticed the 'drain' tube doesn't go to the bottom of the tank. So what's it drain? Are you supposed to remove the drain cap and put a couple psi on the tank to force the diesel out of the out or return line?

I recently replaced my rubber hoses and now fuel is dripping from my 'drain' cap... it's hot out today and when I noticed the big puddle of fuel I opened my filler cap and I hear a lot of air rush out (I assume it wasn't rushing in at least). If you have your filler cap off on a cold day and later it gets warm out, thus now you have some air pressure in your tank, how does air pressure normally be bled from the tank?

Thanks!

-Carl

 

[Recovry4x4]

That is actually an auxiliary tap for a fuel fired heater to draw fuel from the tank. I have also used them as a means to transfer fuel into the tank as well as a secondary pickup when the sock got spooged up.

 

[cucvrus]

That auxiliary fuel pickup line will stop catching/picking up fuel at about a 1/4 tank. It is not planted on the bottom of the fuel tank like the socked main fuel pickup line. May not matter to you but I wanted to mention that for others that may give a hoot. Have a great day.