Mechanical fuel pump 

• A mechanical fuel pump is a device that delivers fuel to the engine. It is usually found on older vehicles that use a carburettor to mix the fuel and air.
• A mechanical fuel pump is driven by the camshaft or the crankshaft of the engine, and it uses a diaphragm or a plunger to create suction and pressure. 
• The fuel is drawn from the tank through an inlet valve, and then pushed through an outlet valve to the carburettor.
• A mechanical fuel pump operates at a low pressure of 10-15 psi (0.7-1.0 bar)
• Mechanical fuel pumps are simple and reliable, but they have some disadvantages compared to electric fuel pumps. For example, they can leak fuel into the engine oil, they can be affected by vapor lock, and they can limit the placement of the fuel tank