A diesel fuel pump, which is the heart and soul of the engine, operates at extremely high pressures and therefore can’t tolerate even a speck of dust in its super-polished interior. Diesel fuel is typically burned in compression-ignition internal combustion engines, which draw in air and subject it to high compression causing it become very hot. At peak temperature and pressure, diesel fuel is injected into the cylinder and self-ignites. After combustion is complete, the combustion byproducts are exhausted out of the engine.
In a Diesel Fuel Injection Pump, the parts that do the actual pumping are called a plunger and barrel, and together they’re known as a pumping element. Roughly analogous to a piston in a cylinder, the plunger is pushed up the barrel by a cam and pulled back down with a spring. Most fuel systems rely at least partially on the diesel fuel to lubricate close tolerance components. It is very critical to keep the diesel fuel clean and free from water and other contaminants. If water is ever evident in the fuel system, it needs flushed out immediately. If the fuel filter is trapping the water you should probably check the fuel tank for more evidence of water.
Traditional pump-line-nozzle injection systems on large truck engines typically use an in-line injection pump with a pumping element for each injector. However the pump used most often in lighter trucks and cars is called a distributor-type pump. The injection pump then pressurizes the fuel and passes it through the injection nozzle. Additionally the injection pump controls the amount of fuel that is injected and sets the injection timing. The injection pump is the most important part of the entire fuel system. Since most diesel engines are now turbocharged, a few tips for prolonging the life of the turbo may be in order. The same oil change intervals mentioned earlier should be followed. The most common failure of automotive turbo is due to hot shutdown. This occurs when the vehicle has been running at a constant speed for a period of time and the vehicle is shut off before the turbo has had time to slow down.
Whenever a fuel injector problem arises, the first thing to do is make sure the fuel screen is clean and not plugged. There’s a 74 micron filter screen at the fuel inlet of the injector. This screen should be removed and cleaned at each 100 hour inspection. The screen should be removed from the same side of the injector to which the fuel line is attached. The injector is another can of worms entirely, but is still quite simple to strip and repair. What you cannot do at home is reset the injection pressure, which requires a bench test rig. Automobile manufacturers rely on emissions test benches to perform development and certification testing. Test benches provide gas concentration data for both real-time evaluation and post-test analysis by monitoring gases and routing them to analyzers using solenoids, stainless steel pipes, and various sensors. The gas analyzers measure the concentration of key gases emitted by automobile engines.
After 80 years of development, the mechanical fuel injection pump is fast becoming obsolete for on-road applications with the introduction of electronically controlled common rail injection.
