Mareeman
I agree with you 100% about tank changing in a cheiftain. Having flown a few thousand hours in them on freight and running out the aux's as a matter of course as it gives you a very accurate fuel flow rate (I could always get 148ltrs into an aux after running it dry, rather than the placarded useable of 142). I have often sat there bored out of my brain waiting for the "low press boost pump" light to come on (there is no "low press fuel" light), and then missed it whilst picking my nose and gazing out the window at the moon or something else really interesting. I also discovered through trial and error that the fastest way to get fuel back to the engine is by changing over the tanks BEFORE turning on the pump. If you have ever operated the cheiftain at high power settings in the cruise i.e. over 200 L/hr, then you discover that you actually need to watch the fuel pressure gauge for signs of a flicker, as the low press pump light will not give enough warning to prevent engine surging.
23 METROS
I think you will find that when a tank runs dry the fuel line has a mixture a fuel and air in it. A bit like when you are sucking the last bit of orange juice out through a straw. The surging is caused by the engine getting alternate hits of fuel and then air. One would expect low fuel pressure to create a lean mixture and thus rough running not surging. Rough running is what occurs when you hit take off power and your main tank selector is not fully open. But that is another story.