The device of any car, whether it is diesel or gasoline, has a power system (in other words, a fuel system). There is an opinion that diesel cars are more picky about fuel quality. It really is. And the repair of such a system is many times more expensive. Today we will consider what a diesel engine fuel system is, its arrangement and major malfunctions.
Device
Conventionally, this system can be divided into two circuits: high and low pressure. The latter prepares the fuel and directs it to the "next level", to the second circuit. The high pressure system performs the function of the final injection of fuel into the combustion chamber of the engine.
The low pressure circuit chain includes a number of structural components. This is a filter, a separator, a fuel drive, a heater, and a pump. Fuel passes through each of the above items. The pump creates pressure in the system, the heater in the cold season heats the “diesel fuel” to the desired temperature (since in the winter it turns into a paraffin slurry), and through the filter the fuel enters a second circuit, no less important in the system. It consists of the following parts:
- High pressure fuel pump. It connects with the filter.
- Nozzles Recently, nozzles with direct fuel injection have gained great popularity. It is believed that they are designed for a more accurate dosage of fuel. The machine does not lose in power, while the consumption decreases.
- Fuel lines - highways through which the mixture enters the cylinders.
Below we will consider the main malfunctions of the diesel fuel system.
Difficult start
Especially often this happens in cold weather. It is believed that starting a diesel engine without preheating in winter is almost impossible. In order to somehow alleviate this situation, manufacturers provided for Arctic fuel, which includes antifreeze additives. But a difficult start does not always mean frozen fuel. If the machine starts poorly even “hot”, most likely, the high pressure pump, namely its discharge elements, has failed. It is also worth checking the lead angle of the fuel supply to the engine. Nozzle wear is possible, due to which the mixture is poorly atomized in the cylinder. In general, the reasons for the difficult start of a diesel engine are many. Therefore, every detail is checked. Glow plugs, improper operation of the pressure regulator, lack of fuel in front of the injection pump can be malfunctioning. Such malfunctions of the fuel system of a diesel engine (Volkswagen T4 is no exception) are accompanied by depressurization of the fuel lines, due to which air enters the pump, which is no longer able to generate the required pressure.
Power drop
It occurs due to wear or damage to the spray guns. Also, such malfunctions of the fuel system of a diesel engine occur due to insufficient fuel that gets into the pump. Since a filter is installed in front of it, it is likely that it is simply clogged.
High consumption
These malfunctions of diesel engine power supply systems arise due to an incorrectly set injection advance angle. Also, increased fuel consumption is a consequence of improper operation of the fuel pump. The injection pressure level of the mixture is too high. In addition, the flow rate increases due to the low compression in the cylinders.
Black smoke from the exhaust pipe
And if it is considered to be a “factory disease” at KamAZ trucks, which the owners simply do not pay attention to, foreign cars smoke is a reason to think seriously. These signs of a diesel engine malfunction indicate poor mix formation in the cylinders, which may be due to late fuel injection. Also check nozzles and valve clearances. The “blackness" itself is formed due to soot and loose closure of the engine inlet / outlet valves.
White and gray smoke
Perhaps the engine has a broken head gasket. If this smoke disappears over time, the motor simply has cooled down. This is normal for northern latitudes.
Hard work
A diesel engine is inherently noisier than a gasoline engine. However, if the vibrations intensified, an early injection of fuel most likely occurred. The diesel engine malfunction is determined by diagnosing injectors. The compression level in the cylinders is also checked. Its minimum level should be 23 kilograms per centimeter cubic. The run-up of indicators between the cylinders does not exceed 5-10 percent. The average diesel engine produces about 27-30 "kilograms". For determination, a special tool is used - a compressometer.
Acceleration Failures
Symptoms - the gas pedal is too short. In this case, adjust the thrust of the accelerator. Also check the air filter. The high-pressure fuel pump may be defective, due to which it cannot generate the required pressure in the system.
“Idle” swim
In this case, check the sealing washers under the nozzles. Look at the mounting of the fuel wire between the filter and the pump. If necessary, tighten more. Also, with such symptoms of a malfunction of the diesel fuel system, the pump base plate is looked for damage. Possible wear of the crankshaft speed regulator . “Idle” swim due to excessive gas pressure in the crankcase - check ventilation.
Engine stalled
If it stalls on the go, check the offset of the injection advance angle. This is a violation of the connection between the drive and the pump. It is also a dirty filter, which causes a shortage of fuel and a low supply pressure. As for the pump itself, it is possible to skew the piston separators or rotor. It is worth noting that the high-pressure fuel pump is the most expensive part in the power supply system of a diesel car. Due to the complex design, the element is difficult to repair, therefore, the cost of restoration is comparable to the price of a new element purchased during disassembly.
Prevention
To exclude malfunctions of the fuel system of a diesel engine (because breaking a diesel engine is expensive and long-term), do not be lazy to carry out preventive maintenance. First of all, you need to flush the system with a frequency of 1-2 times a year. This operation includes dismantling the fuel tank and removing accumulated "sludge" in the fuel filter. Practice shows that at the bottom during operation, a lot of sediment forms, which when driving on an empty tank instantly gets clogged in filters and highways.
Fuel grade
This is especially true for the use of the car in the so-called transitional season. The air temperature has already dropped, and the remaining fuel is sold at gas stations. It loses its fluidity already at -5 degrees. Then it turns into paraffin, which becomes clogged in the pump and filters. Be sure to specify at the gas station what type of fuel will be poured - summer or winter. If it so happened that the temperature dropped sharply, and in the tank there was a summer “diesel fuel”, warm the machine as much as possible with the help of a pre-heater, or if it is a passenger car, connect the household heater to the garage. When starting a diesel engine, every degree is important.
Do not dilute fuel
Some craftsmen, if it is necessary to start a diesel engine in the winter, “fuel” the fuel with gasoline. It is absolutely impossible to do this. Special Arctic additives for diesel have long been sold in Russia, which prevent the formation of paraffin in the tank. In fact, these additives are also added to ordinary summer fuel at gas stations - so it becomes suitable for use in winter. There is nothing illegal about it. But to dilute it with gasoline is simply suicide (meaning for the fuel system).
Warming up in winter
Warm up or not? The fuel system of a diesel engine, the device of which is significantly different from gasoline, also needs this action. After starting the engine, let it run idle for 3-5 minutes, after which drive the first 200 meters in the "gentle" mode for the car. The diesel engine, unlike the gasoline engine, is colder - it warms up much longer. Long idling is also not required, but you should not ignore the above recommendation.
Gas station
Everyone scolds our gas stations for poor fuel quality, they say, at Russian gas stations there is no normal diesel fuel. This is fundamentally wrong. One simple rule: refuel the car with expensive fuel at well-known gas stations. Everyone wants to save money by buying fuel 10-15 percent cheaper than market value, literally lining up in line. However, after a couple of weeks, having got to the fuel repair, they start not blaming themselves, but refueling. In fact, this is so, but nobody forces them there by force. You always have a choice. Remember the main thing - the avaricious pays twice.
How to increase the fuel injection pump resource?
As we said earlier, this is one of the most critical parts of the fuel system.
In order for the high-pressure pump to last longer and malfunctions of the fuel system of the diesel engine pass you by, you need:
- Do not leave the tank “half empty” at night. So on his machines condensate forms, which then penetrates into the nozzles and pump.
- Periodically drain sludge through the drain plug.
- Do not drive on an empty tank and a constantly burning light bulb.
Conclusion
So, we found out the main diesel engine malfunctions. Observing these simple rules, you will significantly extend the life of the system and reduce the risk of "getting into repair."