Description of the contour
The fuel pump is located inside the fuel tank and is connected to the fuel line. The fuel pump will remain on as long as the starter is engaged or the engine is running and the engine control module (ECM) receives a pulse signal from the crankshaft position (CKP) sensor. If no pulse signals are received, the ECM will turn off the fuel pump after 2 seconds with the ignition on or 2 seconds after the engine is turned off. The fuel pump delivers fuel through the fuel rail to the fuel injectors, where the pressure level is maintained at 379 to 393 kPa by the fuel pressure regulator. Excess fuel is returned to the fuel tank.
There are two main fuel control sensors:
- manifold Absolute Pressure (MAP) sensor,
- oxygen sensor (O2S).
Manifold Absolute Pressure (MAP) Sensor
The MAP sensor measures the vacuum in the intake manifold.
If the fuel demand is high, the MAP sensor provides information about a low vacuum, which corresponds to a large throttle opening angle. The engine control unit (ECM) uses this data to enrich the mixture, increasing the opening time of the injector valve to provide the required amount of fuel. As the throttle opening angle decreases, the vacuum increases. This change in vacuum is detected by the collector absolute pressure sensor and the ECM, which reduces the fuel injector start-up time and reduces the fuel supply.
Oxygen sensor (O2S)
The oxygen sensor is located on the exhaust manifold. The oxygen sensor (O2S) provides the ECM with information about the amount of oxygen in the exhaust gases, and the ECM changes the air/fuel ratio using the injectors. The best air/fuel ratio for minimizing harmful impurities in the exhaust gases is 14.7:1, which allows the catalytic converter to work more efficiently.
By constantly measuring and adjusting the air/fuel ratio, the fuel injection system is called a "closed loop" system.
The ECM receives input signals from various sensors to determine the proper amount of fuel to deliver to the engine. Fuel is delivered according to one of a series of conditions called a "mode."