This situation puzzles me: I have two 1000-liter tanks containing biodiesel. A vane pump and metering system draws fuel from both tanks simultaneously, or should. Each has a kind of 'stinger' pipe inserted through the top opening, with hose going from stinger to a T-fitting, thence to the pump. The pump is mounted closer to one tank, call it Tank A, than the other, tank B. Consequently, the hose from Tank B is significantly longer than the hose from Tank A. If it matters, there are about 2.5m of 25mm diam hose from Tank B, and about 1.5m of the same type hose from Tank A. For both tanks, the fuel flow is up through the stinger, over and down through the hose to the T-fitting, thence up through the vane pump and meter, thence out the vehicle fuel tank through 3m of 18mm diam hose and a conventional fuel nozzle.
Here's the mystery: Tank B, the tank more distant to the pump, empties first! This seems completely counter-intuitive to me. I expected both tanks to empty at the same time, or, perhaps, Tank A to empty slightly faster than Tank B. Can anyone explain? This is not some academic exercise, this is a description of what has happened repeatedly since we began using this system 7 months ago.
Paul Mathews