Keep in mind, in a downline, fuel moves to the back of the tank, along with the clunk. If the clunk gets stuck forward then you have a problem but if you are in a dive, inertial forces move the fuel to the BACK of the tank, it will not pool up at the front of the tank and dry out the line. What sometimes happens though is that in a downline, high speed snap, you can snap fuel out of the line due to the intertial forces to the side - and forward since the plane slows down so fast.