Description

About Fuel Pump

The fuel pump is located at the fuel tank and is designed to convey the required quantity of fuel from the tank to the engine at the necessary pressure.

Function

The purpose of a car fuel pump is to convey the required quantity of fuel from the tank to the engine at the necessary pressure.

MECHANICAL FUEL PUMP

Older cars with a carburettor are usually fitted with a mechanical fuel pump (diaphragm pump). This type of fuel supply pump is driven by the camshaft or distributor shaft. It also draws the fuel from the tank and conveys it into the float chamber of the carburettor. The supply pressure is roughly 0.2 to 0.3 bar.

DESIGN OF ELECTRIC FUEL PUMP

The electric fuel pump comprises the following components:

Cover

This contains electrical connections, a check valve (to prevent escape from the fuel system) and a hydraulic outlet. The cover usually also contains the carbon brushes for operation of the commutator drive motor and interference suppression elements (inductors and, if applicable, capacitors).

Electric motor

The electric motor contains an armature and permanent magnets. A copper commutator is standard. Carbon commutators are used for special applications and diesel systems.

Pump section

The pump section is either a positive displacement pump or a flow-type pump.

A broad distinction can be made between electric fuel pumps of the flow and positive displacement type.