THROTTLE BODY

The throttle body is located between the turbocharger and intake manifold (Fig. 15). The throttle body houses the throttle position sensor (TPS) and the automatic idle speed (AIS) motor. Air flow through the throttle body is controlled by a cable operated throttle blade in the base of the throttle body.

FUEL SUPPLY CIRCUIT

Fuel is pumped to the fuel rail by an electrical pump in the fuel tank. A filter, attached to the pump inlet, prevents water and other contaminants from entering the fuel supply circuit.

The vacuum assisted fuel pressure regulator keeps fuel pressure at 380 kPa (55 psi). The regulator uses intake manifold pressure at the vacuum tee as a reference.

FUEL INJECTORS AND FUEL RAIL ASSEMBLY

Four fuel injectors are retained in the fuel rail by lock rings (Fig. 16). The rail and injector assembly bolts in position with the injectors inserted into recessed holes in the intake manifold.

FUEL PRESSURE REGULATOR

The pressure regulator is located downstream of the fuel injector on the fuel rail (Fig. 17). The regulator maintains constant 380 kPa (55 PSI) fuel pressure across the fuel injector tip.

Fig. 16 Fuel Supply System

The regulator has a spring loaded rubber diaphragm that uncovers a fuel return port. When the fuel pump operates, fuel flows past the injector into the regulator. Fuel is restricted from flowing any further by the blocked return port. When fuel pressure reaches 380 kPa (55 PSI), it pushes on the diaphragm, compresses the spring, and uncovers the fuel return port. The diaphragm and spring continually move from an open to closed position keeping the fuel pressure consistent.

FUEL SYSTEM DIAGRAM

Refer to the Component Identification portion of this section for a more complete description of the components shown in Figure 1.

VISUAL INSPECTION

Perform a visual inspection for loose, disconnected, or misrouted wires and hoses before diagnosing or servicing the fuel injection system. A visual check

(1)Check Ignition Coil Electrical Connections (Fig.

2).

(2)Verify the electrical connector is attached to the Canister Purge Solenoid (Fig. 3).

(3)Verify the electrical connector is attached to the Wastegate solenoid (Fig. 3).

(4)Check vacuum hose connections between vacuum source and canister purge, wastegate and barometric read solenoids (Fig. 3 and 4).

(5)Verify the electrical connector is attached to the MAP sensor (Fig. 4).

(6)Verify hoses are securely attached to vapor canister (Fig. 5).

(7)Verify alternator wiring and belt are correctly installed and tighten.

(8)Check Ignition Cable Routing and Attachment (Fig. 6).

(9)Inspect the oil pressure sending unit electrical connector (Fig. 7).

(10)Check both electrical connectors at the distributor (Fig. 7).

(11)Check radiator fan electrical connector.

(12)Check the coolant temperature sensor electrical connection. Inspect battery ground cable connection (Fig. 8).

Fig. 4 MAP and Barometric Solenoid Connections

Fig. 5 Vapor Canister

Fig. 6 Ignition Cable Mounting and Attachment

(13)Inspect the engine temperature sensor electrical connection (Fig. 9).

(14)Check power brake booster and speed control vacuum connections (Fig. 10).

(15)Check engine harness to main harness electrical connections.

(16)Check park/neutral switch wiring connection (Fig. 11).

(17)Ensure relay and battery connections are clean and tight (Figs. 12, 13, and 14).

Fig. 7 Oil Pressure Sending Unit Electrical Connection

Fig. 8 Coolant Temperature Sensor

Fig. 9 Engine Temperature Sensor Electrical Con-

nection

Fig. 10 Power Brake Booster and Speed Control

Vacuum Hose Connections

Fig. 11 Automatic Transmission Electrical

Connections

Fig. 12 Relay IdentificationÐAA and AP Bodies

Fig. 13 Power Distribution CenterÐAG and AJ

Bodies

Fig. 14 Relay IdentificationÐAG and AJ Bodies

(18) Ensure the 60-way connector is fully inserted into the socket on the Engine Controller (Fig. 15). Make sure the wires are not stretched or pulled out of the connector.

14 - 62 FUEL SYSTEMS

(19)Verify the harness connector is attached to AIS motor (Fig. 16).

(20)Verify the harness connector is attached to the throttle position sensor (Fig. 16).

(21)Check hose connections at throttle body (Fig.

16).

Ä

(26) Verify engine ground strap is attached to the intake manifold and the dash panel (Fig. 18).

Fig. 16 Throttle Body Electrical and Vacuum Hose

Connections

(22)Verify hose from PCV valve is securely attached to the intake manifold vacuum port (Fig. 17).

(23)Check vacuum hose connection between vacuum source and fuel pressure regulator (Fig. 17).

(24)Check Fuel Injectors Wiring Connector and Detonation Sensor connector (Fig. 17).

Fig. 17 Electrical, Fuel, and Vacuum Connections

(25) Check Heated Oxygen Sensor connector (Fig.

18).

Fig. 18 Heated Oxygen Sensor

(27)Verify the vacuum and pressure connections on the turbo charger are secure (Fig. 19).

(28)Check the turbo bypass valve hose connection (Fig. 19).

Fig. 19 Hose Connections

(29)Check all vacuum harness connections.

(30)Verify the harness connector is attached to distance sensor (Fig. 20).