Rotax 912 (and probably some of its derivatives) uses an automotive diaphragm pump, from a small Opel or VW or such. The advantage of the diaphragm system is that it can stand it when no fuel flow is possible, perhaps due to the float in the carburettor closing off the entrance.
I suppose gear pumps need to have some kind of bypass to handle this situation adequately.
My 912-powered Apollo Fox was one of the few planes at the field not having an extra electrical fuel pump, even most high-wingers with a Rotax had one. Totally needless, the fuel pump on the engine - which is there anyway - is more than sufficient. Perhaps even in a low- or midwing plane, though I'd not trust myself to speculation in that corner.
PS not to be forgotten: the fuel pump is not merely for pumping fuel from the tank(s) to the engine, it has an important function of keeping sufficient pressure in the fuel tubes so as to avoid vapour-locking.
Last edited by Jan Olieslagers; 6th October 2023 at 16:49.