The fuel metering system is made up of the following parts:

When the ignition switch is turned to the ON position, the PCM energizes the fuel pump relay for 2 seconds allowing the fuel pump to pressurize the fuel system.

An inoperative fuel pump relay will cause a no start.

The accelerator control system is a cable type and there are no linkage adjustments. Therefore, the only specific cable for each application must be used. When work has been performed on the accelerator controls, always make sure that all components are installed correctly and that the linkage and cables are not rubbing or binding in any manner. The throttle should operate freely without binding between full closed and wide open throttle.

The fuel injector assembly is a solenoid-operated device, controlled by the PCM, that meters pressurized fuel to a single engine cylinder. The PCM energizes the fuel injector solenoid (3), which opens a ball valve (1), allowing fuel to flow past the ball valve, and through a recessed flow director plate (2) at the injector outlet. The director plate has machined holes that control the fuel flow, generating a conical spray pattern of finely atomized fuel at the injector tip. Fuel from the tip is directed at the intake valve, causing it to become further atomized and vaporized before entering the combustion chamber. A fuel injector that is stuck partly open would cause loss of pressure after the engine is shut down, so long crank times would be noticed on some engines. Dieseling could also occur because some fuel could be delivered to the engine after the ignition is turned OFF.

The fuel pressure regulator assembly is a diaphragm-operated relief valve with fuel pump pressure on one side, and a regulator spring pressure and intake manifold vacuum on the other side. The regulator's function is to maintain a constant pressure differential across the injectors at all times. The pressure regulator compensates for engine load by increasing the fuel pressure as the engine vacuum drops. The fuel pressure regulator is serviced as a complete assembly. With the ignition ON and engine OFF (zero vacuum), fuel pressure should be 284-325 kPa (41-47 psi). Whenever the pressure is too low, poor performance and a DTC P0171 could result. Whenever the pressure is too high, excessive odor and a DTC P0172 could result.

The nonadjustable, throttle shaft-driven TP sensor is mounted on the throttle body assembly opposite the throttle cam lever. The TP sensor senses the throttle valve angle and relays the information to the powertrain control module (PCM). Knowledge of throttle angle is needed by the PCM to properly control the injector control signals (pulses).

Engine idle speed is controlled by the PCM through the IAC valve (1) mounted on the throttle body. The PCM sends voltage pulses to the IAC valve motor windings causing the IAC valve pintle (3) to move IN (toward the seat) or OUT (away from the seat) a given distance (a step or count) for each pulse. The commanded location (steps away from the seated position) can be observed as a number of counts displayed on a scan tool. The pintle movement controls the airflow around the throttle valve (2), which in turn, controls engine idle speed: Pintle Extended=Decrease RPM=Lower Counts. Pintle Retracted=Increase RPM=Higher Counts.