The sequential electronic fuel injection system calculates and delivers fuel to the engine cylinders in the order in which they are fired. The injectors are controlled by the engine control module (PCM). Based on information from various sensors, the PCM controls the fuel injectors by varying the pulse length, i.e., the length of time the injectors are open. The amount of fuel is constantly adjusted to provide the optimal ratio for hot or cold starting, warm-up, idle and acceleration. The throttle assembly serves only to control the amount of air supplied to the engine cylinders.
Fuel is supplied from the fuel tank to the fuel system through metal tubes attached under the bottom of the vehicle. The electric fuel pump, fuel level sensor and pressure regulator are located in the fuel tank.
The fuel pump relay is controlled by two electrical circuits. The first circuit is controlled by the engine control unit (PCM), and the second by the ignition switch. If the engine fails to start after the ignition is turned on, the PCM will deactivate the fuel pump relay after 2 seconds. The next time the engine is started, after the first pulse from the camshaft position sensor, the relay activates the fuel pump.
The exhaust system consists of an exhaust manifold, an exhaust pipe, a central and rear muffler and a catalytic converter. The catalytic converter purifies exhaust gases.
(The material is republished from an online website ToyotaMan.ru)