However sometimes that wont work. In some applications there may even be clearance issues where a mechanical pump cannot be used.

Know How Notes Fuel Pump Basics
Electric or mechanical fuel pump. Although mechanical and electric fuel pumps each have their share of pros and cons sometimes it all comes down to practicality. One low pressurehigh volume supply pump in the tank and one high pressurelow volume pump on or near the engine. The cross member was in the way of the mechanical fuel pump. How should you wire an electric fuel pump when do you need an electric fuel pump. Electric pumps offer a larger variety of flow rates and pressure outputs in comparison to mechanical pumps. Upgrading to an electric pump is needed when higher fuel pressures are required like boosted applications nitrous and fuel injection.
Usually a mechanical pump is preferred over an aftermarket electric fuel pump. There are two different types of fuel pumps mechanical and electrical but mechanical is quickly dying out. In my old 47 chevy the engine i had swapped in had an issue. Often carbureted engines use low pressure mechanical pumps that are mounted outside the fuel tank whereas fuel injected engines often use electric fuel pumps that are mounted inside the fuel tank and some fuel injected engines have two fuel pumps. The pump is mechanically driven by a lobe on the engines camshaft by the pump being bolted to the engine block or head. Thats a big plus zach baker of quick fuel technology explains.
The obvious advantages of a mechanical pump are that they dont make any noise and they dont require any additional plumbing or wiring. Mechanical fuel pumps were a part of many earlier cars typically the ones that were built before the 1970s. They tend to be more reliable.