Diesel injection pump. High pressure fuel pump
Diesel injection pump. High pressure fuel pump

The main difference between diesel engines and gasoline engines is a different arrangement of the fuel system and injection system. The most important element in the design is the injection pump of a diesel engine. This is a high pressure fuel pump.

What is injection pump

This equipment is considered one of the most complex among other diesel power units. The device performs the main function. It delivers fuel to the combustion chambers at very high pressure.

diesel engine injection pump
diesel engine injection pump

This is necessary to supply the combustible mixture to the combustion chambers of the engine under a certain pressure, and only at the right moment for this. The portion of the given mix is very precisely measured by means of electronics. Also, the portion corresponds to the load.

Evolution of injection pump

The government of many countries around the world has significantly tightened environmental standards for the emission of harmful substances. This has led to the fact that the mechanical high pressure fuel pumps of the diesel engine began to be gradually replaced by electronic equipment. The mechanics could not cope with the correct dosing of the fuel mixture in the required accuracy. Besides,mechanics could not quickly respond to every change in the operating mode of the power unit.

The most famous electronics manufacturers have offered modern fuel mixture control systems. The introduction of electronics made it possible to reduce the instability of fuel combustion, and also reduced uneven idling.

Some devices had a special valve in their design for quick action. This led to the division of the process of supplying the fuel mixture to the chambers into two parts. This technology has significantly reduced the severity of fuel combustion.

Precise injection control also helped to reduce emissions of toxic substances into the atmosphere. In new engines, the mixture burns out completely, and the increased efficiency has made it possible to increase efficiency and increase the final power.

Distribution-type equipment is equipped with electronic control. Electronics regulates the position of the dispenser. Also included is a special valve that allows you to get ahead of the injection process.

Types of injection pumps

There are several types of pumps according to the type of injection.

diesel engine injection pump
diesel engine injection pump

So, there are direct action devices, as well as battery equipment. In the latest systems, torque control processes are assigned directly to the nozzles and electronic control systems.

Direct acting pump

The injection pump of a diesel engine with direct action has a mechanical device. The drive is based on a plunger and a sleeve. It is calledplunger pair. Any processes on equipment of this type take place at the same time. A separate part of the pump delivers fuel in the required dose to each combustion chamber of a diesel engine. As for pressure, it is created by the movement of the pump plunger. This equipment is equipped with many diesel foreign cars. There is also a high-pressure fuel pump of a diesel engine (Volkswagen is no exception) according to this principle.

Battery injection pump

Here, the difference from a traditional pump is that the plunger drive is affected by pressure directly in the cylinder itself.

repair of injection pump of diesel engines
repair of injection pump of diesel engines

But besides this, such an effect can be exerted through special springs. There are also devices with hydraulic accumulators, which are most often installed on powerful, but slow-revving engines.

Needless to say, hydraulic accumulator pumps feature separate injection and discharge processes. The combustible mixture is pumped into the accumulator under high pressure and only then enters the combustion chambers. This approach allows for more efficient atomization as well as optimal mixture formation, which is excellent for any load. Among the disadvantages of such a system, one can single out even greater complexity of the equipment, which does not contribute to popularity. Modern engines use equipment based on solenoid valves and an electronic control system.

Distribution pump

These elements, in comparison with in-line ones, are equipped with one or twoplungers that serve all combustion chambers. The mass and overall dimensions of these devices are much smaller. The quality of their work is much higher.

diesel engine diagnostics
diesel engine diagnostics

But these systems are short-lived. Often, repair of high pressure fuel pumps of diesel engines was required. This determined the application of the equipment - passenger cars.

In-line pumps

This equipment is equipped with plunger pairs. There are as many of them as there are cylinders in the engine. These parts are mounted in a housing, where there are special channels for pumping and discharging diesel fuel. To drive the plunger, a special camshaft is used, which is driven from the crankshaft. For the pump to work, the plunger pairs must be pressed against the cams. This is done with springs.

When the camshaft moves, the cam finds the pusher, which at that moment moves along its sleeve. When the element moves, opening and closing of the holes for the inlet and outlet of fuel is performed. Thus, pressure appears in the system. As a result, the discharge valves open and the fuel moves through the fuel line to the injectors. This is the job of a diesel injection pump.

To adjust the plunger is rotated in its sleeve. In order to perform this rotation, the device has a special gear that meshes with the rack. The latter is directly connected to the accelerator pedal. The upper part of the plunger is made inclined. When turning, you can change the numberdiesel fuel.

This design of the in-line pumps ensures high reliability.

diesel injection pump price
diesel injection pump price

The mechanisms are lubricated by means of engine oils from the lubrication system of the unit. Therefore, low quality fuel can be used. These pumps are used in large trucks and were used in cars until 2000.

Diesel injection pump unit

On the example of a distribution injection pump, we can consider a fundamental device. So, pumps are single-plunger or double-plunger. At the same time, one section of the apparatus can supply a combustible mixture to several nozzles.

Thus, the equipment consists of a pressure reducing valve, an all-mode regulator, a drain fitting, a pump section housing, together with a plunger pair and valves. In addition, the devices include an element for pumping fuel, a hatch for adjusting the injection advance, a housing, a solenoid valve and a plunger drive device.

As you can see, the equipment has a complex structure. In the event of a breakdown, diagnosing a diesel injection pump will be a difficult task. And it will be very difficult to repair the system even in a garage.

Causes of malfunctions

The cost of these devices is quite high, and the pump itself is very demanding on the quality of fuel and lubricants. If a diesel car is used on poor fuel, then it necessarily contains various solid particles. All this affects the operation of the plunger pair, which has a minimum tolerance. Alsolow-quality "diesel fuel" easily disables the nozzles. Considering the complexity of a modern diesel injection pump, the price of refueling low-quality fuel can be very expensive. By the way, the pump itself costs about $300.

Among the most popular pump and injector breakdowns, the following are distinguished:

  • high consumption;
  • smoky exhaust;
  • noise and other extraneous sounds;
  • power droop;
  • difficult to start.

Of course, these breakdowns can be caused by other reasons.

operation of the injection pump of a diesel engine
operation of the injection pump of a diesel engine

And to find out if the repair of high-pressure fuel pumps of diesel engines is needed, a special stand is needed. This equipment is only available at service stations that specialize in such equipment. Modern pumps do not have those adjustments that would allow diagnostics. Therefore, you will have to take the help of professionals.

Machine Repair

The need for repairs can be caused by a variety of reasons.

volkswagen diesel engine injection pump
volkswagen diesel engine injection pump

Many breakdowns cannot be fixed by hand. However, if the repair comes down to replacing worn parts, this is easily done in the garage. But you still have to adjust the equipment at a specialized stand.

So, one of the reasons is the wear of the injection pump of a diesel engine. Determining this is easy enough. The power plant will run too unevenly and loudly. It also makes it harder to start and lose power. About low quality fuel has already been said. More onserviceability affects electronics. For repair, it is often necessary to simply replace what has worn out. But for this you need to disassemble the device. You can do it yourself, but without proper knowledge, it is better to turn to professionals.

So, we found out what types of high pressure fuel pumps are and examined the reasons for their failure.