Brown davis aux tank

[Xavman80]

I have had a brown davis aux tank fitted and it issues only using 45l out of it then not drawing any more into the main tank
Anyone else had this with a bd tank? Is there a small transfer pump in the main tank that draws the fuel from the aux tank?

 

[WestAus80]

Sounds like they didnt extend the fuel cut off switch on the sender unit.