A fuel pump is an essential component on a car or other internal combustion engined device. Fuel has to be pumped from the fuel tank to the engine and delivered under low pressure to the carburetor or under high pressure to the fuel injection system. Some fuel injected engines have two fuel pumps for this purpose: one low pressure/high volume supply pump in the tank and one high pressure/low volume pump on or near the engine.
In earlier cars built before the late 1970s, the pump was mechanically driven by a lobe on the engine's camshaft and therefore bolted to the engine block. It created negative pressure to "suck" the gasoline through the lines. However, the negative pressure from the pump, in combination with heat from the engine and/or hot weather, could cause the gasoline to boil. The fuel pump, designed to pump liquid, not vapor, would be unable to suck more gasoline to the engine, which would cut out. This condition is known as "vapour lock". Also a suction pump could suck in air through (difficult to diagnose) faulty hose connections. A leaking connection in a pressure line will show itself immediately
Nowadays, the fuel pump is located inside of the fuel tank and is usually electric. The pump creates positive pressure in the fuel lines, pushing the gasoline to the engine. The higher gasoline pressure raises the boiling point. Placing the pump in the tank puts the component least likely to handle gasoline vapor well (the pump itself) farthest from the engine, submersed in cool liquid. Another benefit to placing the pump inside the tank is that it is less likely to start a fire. Though electrical components (such as a fuel pump) can spark and ignite fuel vapors, liquid fuel will not explode (see explosive limit) and therefore submerging the pump in the tank is one of the safest places to put it. In most cars, the fuel pump delivers a constant flow of gasoline to the engine; fuel not used is returned to the tank. This further reduces the chance of the fuel boiling, since it is never kept close to the hot engine for too long.
Engine configuration is an engineering term for the layout of the major components of an internal combustion engine. These components include cylinders, pistons, crankshaft or crankshafts and camshaft or camshafts.
For many automobile engines, the term block is interchangeable with engine in this context, for example V block and V engine can often be used interchangeably in American English. This is because the most common forms are all based on a combined engine block and crank case that are milled from a single piece of cast metal. The locations of the major components are largely determined by the shape of this one component.
The standard names for some configurations are historic, arbitrary, or both, with some overlap. For example, the cylinder banks of a 180° V engine do not in any way form a V, but it is regarded as a V engine because of its crankshaft and big end configuration, which result in performance characteristics similar to a V engine. But it is also considered a flat engine because of its shape. On the other hand, some V-twin engines which have none of the typical V engine crankshaft design features and consequent performance characteristics are also regarded as V engines, purely because of their shape. Similarly, the Volkswagen VR6 engine is a hybrid of the V engine and the straight engine, and can not be definitively labeled as either. The names W engine and rotary engine have each been used for several unconnected designs. The H-4 and H-6 engines produced by Subaru are not H engines at all, but boxer engines.
All text of this article available under the terms of the GNU Free Documentation License (see Copyrights for details).