Diesel Fuel System Components

The fuel system and the absence of an ignition system are the main differences between a diesel engine and its gasoline-powered counterparts. Gas engines are called spark ignition engines because they rely on a spark provided by the ignition system to ignite the air/fuel mixture in the combustion chamber. Combustion in a diesel engine, which is called a compression ignition engine, is initiated when atomized fuel is injected into highly compressed hot air in the combustion chamber or a pre-chamber.

To raise the temperature of the air in the cylinder to the diesel fuel’s self-ignition temperature, diesel engines have much higher compression ratios than gas engines, typically 17-25:1. To enable fuel to be injected against such high pressure, special fuel injectors and a high-pressure injection pump are required. There are mechanically controlled pumps, and electronically controlled pumps like those on modern common rail systems, where fuel is supplied to electronically controlled injectors through a common rail.

The exception to the above is with systems that use mechanically or hydraulically actuated unit injectors. In these systems, the high fuel pressure needed for injection is developed inside the injector. Mechanical systems are camshaft operated, while hydraulic systems use engine oil supplied by a high-pressure pump. All systems have a low-pressure pump that transfers fuel from the tank to the injection pump or unit injectors. The fuel is filtered along the way but the filters on diesel engine vehicles commonly incorporate a water separator. Diesel fuel absorbs water, which can cause rust and corrosion to form in the fuel system and wear components like injectors.

Because the air in the cylinders of a diesel engine must get very hot for the fuel to ignite, diesel can be difficult to start when ambient temperatures are extremely cold. Not only is the intake air cold, but the cold metal of the engine can absorb the heat of compression, preventing ignition. To aid cold starting, many diesel engines have glow plugs threaded into the combustion chamber or pre-chambers. As the name suggests, glow plugs contain a heating element that gets so hot it glows when current is applied. Operation varies according to the vehicle, but in general, the glow plugs should operate for a period of time when the engine is cold, to heat the air and ignite the incoming fuel.

In addition to a complete selection of replacement fuel injectors, injection pumps, filter/water separators, and glow plugs for all types of diesel engines and fuel systems, we also carry components like fuel injection control modules, injector driver modules, glow plug control modules, glow plug relays, high-pressure oil pumps, pressure regulators and pressure sensors that are used on many modern diesel applications. Plus we have the related necessities like high-pressure fuel lines, return lines, injector sleeves, seal and gasket kits, and valve cover gaskets with a molded-in injector and glow plug harnesses. Modifying the fuel system to increase fuel flow will generally improve the power output of any internal combustion engine, but the right mods are critical for increasing diesel engine horsepower because of the way a diesel engine operates and the unique nature of diesel fuel. We understand that high-powered diesel engines have special fuel system needs, and offer injectors, injection pumps, fuel/water/vapor separators, lift pumps etc. that can meet them.