With a liquid, suck is a poor description. If you try and pump more than the tank pressure (~14psi @SL) + gravity head will force through the pipework to the pump, you will get a partial vacuum somewhere in the line and/or cavitation in the pump. Fortunately, we have known about this problem for the last couple of centuries, maybe longer, so I think it is a given that the plumbing is of sufficient dimensions that this should not be an issue, at least on takeoff. There is probably a regulation somewhere that states how much oversupply a fuel system should be able to produce - there certainly is for piston engines.