1982 300SD sucking air from fuel tank

[Sapperbmet]

I have a 1982 300SD that I recently picked up.

I have experienced this problem twice now.

When the fuel guage reaches 1/8 tank, there seems to be a significant chance that I will start drawing air into the fuel system. Lesson Learned, fill up before the tank reaches 1/8.

I am curious if this is common problem, or if my fuel level sensor is on the fritz.

I have also heard of a problem with one type of fuel pump becoming vapor locked, is there a possibility that this is what I'm experiencing?