What Are the Functions of the Fuel Pump?

by Johnno CaryUpdated August 06, 2023
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Classic Car Engine Refurbished image by Janet Wall from Fotolia.com

Vehicle engine systems require a constant supply of fuel, which is produced via a fuel tank. The correct amount of fuel is drawn from this tank and propelled into the internal combustion engine via a fuel pump, all of this is the fuel system. There are different types of fuel pumps, whihc all differ in their fuel efficiency and engine performance. Electric motors of course do not have this, but this article will help clarify how a fuel pump works.

Fuel Pump Function

Fuel pumps pump the fuel supply from the vehicle’s fuel tank throught he fuel filter to the engine and also distribute fuel under low pressure to the carburetor or to the fuel injection system under higher pressure. Carburetor engines utilize low pressure pumps, which are located outside of the fuel tank. Fuel-injected engines typically utilize electric fuel pumps mounted in the fuel tank which are high-pressure pumps.

Mechanical Fuel Pump

Mechanical pumps typically contain a flexible diaphragm. In the case of a diesel engine, it would be pumping diesel fuel. The fuel injector chamber volume is decreased or increased by flexing the diaphragm. A lever on the pump is operated via the camshaft, which pulls down the diaphragm and enables fuel to be drawn into the in-tank injection pump. A diaphragm spring pulls the diaphragm up, applying force that enables fuel to be expelled from the pump and into the combustion chamber via direct injection.

Electric Fuel Pump (Inlines)

Electric pumps or generate positive electrical pressure in fuel lines, which drives fuel flow to the internal combustion engine from the gas tank. An ignition switch activates a relay that manages the higher current necessary to increase fuel pressure.

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