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Automotive fuel delivery systems in cars are of two types: one system uses a carburetor and a mechanical pump and the other delivers fuel through electronic fuel injection and an electric pump. The former works by using a vacuum to draw fuel into the engine with the help of a mechanical pump, while the latter delivers fuel by squirting a mist into the combustion chambers.

Unlike carbureted cars, fuel injected cars do not use a pre-existing force such as a vacuum to draw fuel into the engine, so the electronic fuel pump must be mounted inside the fuel tank. Almost all vehicles have been using the electronic fuel injection delivery system since the mid-1980s so the fuel delivery problems that will be discussed in this article will involve fuel injected cars.

Clogged Fuel Injectors

Clogged fuel injectors do not produce the normal amount of fuel with each squirt, which eventually causes the fuel to lean out. If the mixture of fuel and air becomes too lean, a lean misfire could result which leads to loss of power and increased hydrocarbon emissions. Fuel injector clogging is often due to the buildup of olefins, waxy substances that are natural components of gasoline.

In petroleum manufacturing, detergents and fluidizers are added to the fuel in order to thin out olefins. However, some manufacturers, in order to increase their profit margin, cut back on the amount of detergent or fuel additives, creating cheaper but olefin-rich fuels.

Clogged injectors can be cleaned by using fuel additives and on-car or off-car cleaning. Polyether Amine is one of the most recommended fuel additives. It is on the expensive side but it cleans not only the fuel injectors but also the valves and the combustion chambers without the need for any additional additives.

On-car cleaning means that you do not have to remove the injectors to get rid of the deposits. This cleaning process makes use of a pressurized tool in order to feed the fuel into the injector while the engine is running. A problem with on-car cleaning is that some deposits are very difficult to remove and if this happens, you may need to subject your car to off-cleaning.

Off-car cleaning is a heavy task that requires the help of a qualified auto repair shop like Off-car cleaning works by using a fuel injector cleaning machine that has an ultrasonic bath and a reverse-flush feature to ensure total removal of deposits.

Fuel Pump Problems

The engines of fuel injected vehicles are highly sensitive to fuel pressure. If there is high fuel pressure, the engine runs rich, increasing its fuel consumption as well as carbon monoxide emissions. It may also exhibit surging and a rough idle.

A low fuel pressure, on the other hand, may prevent the engine from starting or may cause it to run poorly. This condition may also lean to a rough idle and lean misfire.

The method of checking the fuel pressure depends on the brand of the vehicle. Cars installed with the European fuel injection system use the static pressure test with both the engine and the ignition turned off. Asian vehicle manufacturers recommend the use of a pressure test involving the fuel rail while the engine is running. You can visit your auto repair shop to have your vehicle’s fuel pressure checked.

Dirty Fuel Filter

A fuel filter prevents impurities from making their way into the combustion chambers. Impurities are necessarily removed because they can negatively affect the performance of your vehicle. Over time, impurities can build up on the filter and prevent fuel from reaching the engine.

Hence, manufacturers recommend the replacement of fuel filters every 12,000 miles. You can replace your dirty and clogged fuel filters with a new one by yourself but if you do not have the mechanical skills, it is better to let your qualified auto repair shop remove and replace it.

Water in Fuel

The presence of water in your fuel can cause heavy damage to your engine. Water decreases the ability of fuel to lubricate and it can blow injector tips. During cold weather, water can also decrease the flow rate of fuel or make it freeze.

To remove water from your fuel, you can use the methods of coalescing or stripping. Coalescing allows water to separate from fuel by using gravity and low flow rates while stripping uses a medium that is treated with silicone to block the flow of water while allowing fuel to flow freely through it.