Fuel System

Fuel System

Fuel System Schematic:

The fuel system consists of a fuel tank with reservoir, fuel pump assembly, fuel supply and return lines, fuel filters, fuel rail, fuel injector, and fuel pressure regulator (Figure 1).

When the ignition switch is in the ON or START position, power is supplied to the fuel pump relay and to the Powertrain Control Module (PCM). The fuel pump is commanded on by the PCM grounding the coil in the fuel pump relay. The fuel pump is turned on via the inertia fuel shutoff switch whenever the ignition switch is in the ON or START position. If the PCM detects that the engine has not started or has stopped, it will turn off the fuel pump after 1.5 seconds. This is done to reduce the risk of draining the battery and damaging the fuel pump. The inertia fuel shutoff switch is a safety device which interrupts fuel pump power in the event of a collision. If the inertia fuel shutoff switch is "tripped", it must be reset by depressing the button on top of the switch. The switch is located on the LH side of the kick panel, below the hood release handle.

Fuel Filter

Fuel Filter:

The fuel filter (Figure 2) strains particles from the fuel through a paper element. This filtration process reduces the possibility of an obstruction in any of the fuel injector orifices. This vehicle uses a specially designed fuel filter that has a metal case in order to withstand high fuel pressure.

Fuel Injector

Fuel Injector:

The fuel injectors (Figure 3) are electronically controlled solenoid valves that control fuel flow to the engine. The injectors are controlled by the Powertrain Control Module (PCM), the fuel pressure regulator, and the intake manifold vacuum. When the PCM sends a signal to the injector, the coil in the injector pulls a ball back and fuel is released into the intake manifold through the nozzle. The injected fuel is controlled by the PCM in terms of injection pulse duration. These injectors are side feed type injectors.

Fuel Pressure Regulator

Fuel Pressure Regulator:

The fuel pressure regulator (Figure 4) maintains the fuel pressure at 294 kPa (43 psi). Since the injected fuel amount depends on injection pulse duration, it is necessary to maintain the pressure at the above value. The fuel pressure decreases as the vacuum increases. At idle when vacuum is applied, the fuel pressure is 235 kPa (34 psi). When no vacuum is applied, the fuel pressure is 294 kPa (43 psi).

Fuel Pump

Fuel Pump:

The Fuel Pump (FP) filters solid particles from the fuel and allows the fuel to be transmitted from the fuel tank to the engine. The FP with a fuel damper is an in-tank type. This means the pump and the damper are located in the fuel tank. The FP (Figure 5) has an internal motor which creates pressure in the fuel lines. The FP is controlled by a fuel pump relay, which is controlled by the Powertrain Control Module (PCM).

Fuel Temperature Sensor

Fuel Temperature Sensor:

The fuel temperature sensor (Figure 6) is located in the fuel tank, clipped onto the fuel tank baffle. This sensor is an input into the Powertrain Control Module (PCM). Its data is used primarily by the PCM in calculating the operation of the Evaporative (EVAP) emission system.

Fuel Pump Relay

Fuel Pump Relay:

The Fuel Pump (FP) relay (Figure 7) supplies voltage to the FP when activated by the Powertrain Control Module (PCM). The PCM activates the FP relay for five seconds after turning the ignition key ON, and when the engine is cranking or running. The PCM deactivates the FP relay 1.5 seconds after the engine stops. The voltage supplied from the FP relay allows the FP motor to operate. When the PCM receives a 120 degree signal from the Camshaft Position (CMP) sensor, it knows that the engine is rotating, and causes the FP relay to activate. When activated, the FP relay supplies the FP with voltage, which allows it to operate continuously as long as the engine is running. If the PCM does not receive a 120 degree signal when the ignition switch is ON, the engine is stalled. The FP relay is deactivated and prevents battery discharging, thereby improving safety.

Inertia Fuel Shutoff Switch

Typical Inertia Fuel Shutoff (IFS) Switch:

Inertia Fuel Shutoff Location:

The Inertia Fuel Shutoff (IFS) switch (Figure 8) is used in conjunction with the electric fuel pump. The purpose of the IFS is to shut off the fuel pump if a collision occurs. It consists of a steel ball held in place by a magnet. When a sharp impact occurs, the ball breaks loose from the magnet, rolls up a conical ramp and strikes a target plate which opens the electrical contacts of the switch and shuts off the electric fuel pump. Once the switch is open, it must be manually reset before restarting the vehicle. The IFS location can be seen in Figure 9.