Yeah its the extremely high pressure the fuel is in injected at that allows the engine to get the same amount of energy on less fuel. Here is a generic bosch di setup which is what ford's ecoboost lineups use some variants of.
This is a description of the 3.5 ecoboost system.
Intake and Fuel System
The fuel system on these engines has two sides: a low-pressure system and a high-pressure system. If you’ve worked with DI diesels, then the concept isn’t new to you. The low-pressure system is a mechanical returnless system consisting of an ordinary-looking electric fuel pump mounted inside the gas tank and a three-port fuel filter. Although it technically does have a “return,” via the third fuel filter port, it is still considered a returnless system. The low-pressure pump supplies 65 psi of fuel pressure through the lines leading to the high-pressure pump.
The driver module controls the pump’s speed by duty cycling the pump’s ground circuit. The low-side pressure system has a fuel pump driver module that is commanded by the PCM, similar to an electronic returnless system.
The low-side pump operation is unique. When the courtesy lights are activated, either via the remote key fob or door ajar switches, the power saver relay inside the smart junction box (non-serviceable relay) sends a “wake up” voltage to the PCM.
When the PCM wakens, it turns the fuel pump relay on for two seconds, priming the low-side fuel system. This is done to remove any fuel vapor inside the lines at the high-pressure fuel pump. However, when the PCM receives a valid rpm signal, it actives the fuel pump driver module, which then turns on the fuel pump.
There is no low-side pressure sensor, yet the PCM does control the low-side pump speed via the control module. The low side has two speeds: low and high.
To achieve a low speed, the PCM sends a 37% duty cycle signal to the fuel pump driver module (FPDM), which in turn, operates the pump at around 60% capacity. If the PCM determines a need for higher fuel delivery, it can increase its duty cycle to 47%, which will raise the low-side pump’s operating capacity to 100%.
Low-side pressure must be tested using a conventional fuel pressure gauge. The early models have a test port on the accumulator. Later models will require a test adapter hose to be installed.
The pressure accumulator on the low-side lines is used to help prevent fuel vaporization. The low-side pressure system uses a more high-tech version of the old “inertia switch” that we’ve seen on Ford vehicles since the early ‘80s.
It uses what is called an “event notification system.” With this system, the restraints control module (RCM) will notify the PCM or the FPDM (depending on model) directly to shut down the pump if a crash is detected. Under normal operation, cycling the ignition will restore fuel pump operation from a collision detection shut-down.
That is, when everything is performing as it is designed. That detail is important to remember because as repair techs, we usually only see them when something isn’t working as designed. So obviously the ability to scan the RCM, at least to look for collision detection codes, has become a part of diagnosing an inoperative electric fuel pump.
The high-pressure system consists of a high-pressure fuel pump that is mechanical and driven by a special four-point camshaft lobe that is only for pump operation. The plunger action of the high-pressure pump boosts fuel pressure up to 2,150 psi.
At these pressures, it is critical to exercise caution! High-pressure fuel can cut the skin, injecting fuel into the blood stream, which can be fatal.
The high-pressure fuel is in the metal line leaving the pump to the rails as well as the fuel rails. There is also no return line in the high-pressure system. The high-pressure pump mounts on the left valve cover. Pressure in the high-pressure system swings widely with rpm and demand.
Pressures here will swing from as low as 1,000 psi to 2,150 psi depending on conditions.
Pressure is controlled by balancing the volume through the pump and into the rail versus the volume passing through the injectors. One complete revolution of the camshaft produces four strokes of the high-pressure pump.
At maximum, these four strokes equal 1 cc of fuel delivered to the rail. If met with a dead end, that 1 cc of fuel would raise the rail pressure by about 800 psi. The injector cycling will vent that fuel into the cylinders at around 21 cc per second.
The PCM raises and lowers the high-side fuel pressure by pulsing the fuel inlet valve (solenoid) on the side of the pump.
The inlet valve controls not only the amount of fuel that enters the pump chamber, but also the amount that bleeds back into the low-pressure system when the pump’s plunger pushes the fuel out.
The more the pump is filled, and the less that bleeds back into the low side, the higher the pressure will be in the rails. The PCM monitors a fuel rail pressure sensor to determine the needed action at the volume regulator. The pressure sensor is mounted to the top of the left-hand rail.
The gasoline DI injector is unique. The injector is opened purely by electrical pulse width like a conventional gas engine injector.
The GTDI injectors mount underneath the lower intake and are noticeably unique in shape to allow them to be inserted into the head. Due to the much higher fuel pressures, they are less likely to become fouled with deposits than a conventional gasoline injector. The high-pressure spray pattern also increases fuel atomization.