'FUEL PUMP: Indispensable for your Car'

FUEL PUMP: Indispensable for your Car

By William at 06/04/07 12:21

A fuel pump is an indispensable component on any internal combustion engined device. Fuel from the fuel tank has to be delivered to the carburetor at low pressure, or to the fuel-injection system at high pressure.

In older cars a lobe mechanically drives the pump on the engine's camshaft. The pump consists of a flexible diaphram that has a variable volume fuel chamber on one side. Check valves are fitted to the inlet and outlet of this chamber, with one on its inlet and the other on its outlet. The fuel in that chamber is let out through the outlet check valve by the lever, which is operated by the camshaft, which moves the diaphram to reduce the volume. A return spring inside the chamber increases the volume to draw fuel in through the inlet check valve.

The pump creates negative pressure, which draws the fuel through the lines. The low pressure existing between the pump and the fuel tank, combined with heat from the engine, can vaporize the fuel in the supply line. This results in lack of fuel as the fuel pump is designed to pump liquid and not vapor and is unable to suck fuel into the engine. Hence the engine to stalls. This condition is different from vapor lock in which case high engine heat boils the fuel in the lines also leading to fuel wastage. Mechanical automotive fuel pumps generally generate only around 10-15 psi, which is more than enough for most carburetors.

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