Vacuum in fuel tank?

[per eriksson]

Is it supposed to be vacuum in the tank?
My gut tells me it shouldn't be like that.

Tell me I'm right

[Capt Kirk]

Vacuum = bad.

could be a clogged breather tube.

[psfred]

I think the tank vent tube (rubber) ends somewhere under the car near the fuel tank. If this gets plugged, you get vacuum in the tank, and poor fuel delivery, running troubles, etc.

In the US we have a wasp that builds a nest made of mud for it's young in small holes -- quite common to find such hoses plugged!

Peter

[kweimer]

The vacuum in your tank can also cause your tank to collapse---I have had it happen. The bottom of my tank was pulled in enough to displace three or four gallons---with the result that I "ran out of diesel fuel" when I thought I still had 1/4 tank of fuel. I made this discovery when I filled up and tank would take only about eight gallons. After looking under car and seeing the bottom "caved in", I remembered that whooshing noise I had been hearing whenever I removed the fuel cap. On the 1970 220D the exit of the vent tube is on the side of the fender just behind the bumper. May be different on yours. I was able to "fix" tank by injecting compressed air.
Ken

[Gray Market Survivor]

I seem to have the same problem now. I wonder if it is because of the cold weather and the fact that the tank vent is so close to the ground. It has only been in the days with subzero temps and long drives where I have the tank vent problem. I will check it out and let you know...

Best regards,