The high pressure pump (also called “injection pump”) is a mechanical part of the injection system, which has the task of receiving the fuel from the fuel supply circuit and place it under pressure before entering the injectors rail.
Why an injection pump pressurizes the fuel? Because gasoline or diesel cannot just arrive into the combustion chamber simply by gravity, much less to drip. In fact, an injector is designed to “nebulize” and not to sprinkle the fuel; this is because nebulization allows a much more precise and comprehensive spreading of fuel, but this assumes that the fuel was put into pressure. In fact, the highest the pressure the easiest it will be to get precise and sequential injections (not to mention the pre-injections and post-injections).
The injection pump fulfills this task: it leads the fuel to the optimal pressure and keeps it there while the motor is running.
In diesel engines with last generation Common Rail systems operating pressures can reach up to 2.200 bar, while in gasoline engines it can reach 100 bar. Between the two systems the pressure differences are so high since the composition of the two fuels is fundamentally different (diesel and gasoline have different densities), and because of that the ignition of the two fuels takes place with different dynamics. Diesel will trigger by self-ignition, for this reason it should be brought to higher pressure, because higher pressure = higher temperature. Gasoline instead, ignites due to triggered spark from the spark plug, therefore high temperature and pressure are not necessary.
Common problems encouutered due to overuse or just passage of time:
- – Vehicle wrenching
- – Vehicle that does not render
- – Vehicle that does not start or turns off while driving
- – Total engine failure
