FUEL SYSTEM DIAGRAM

The 3.0L MPI system is managed by the engine controller. The controller receives inputs from various switches and sensors (Fig. 1). Based on these inputs, the engine controller adjusts ignition timing and idle speed through various output devices. Refer to the Multi-Point Fuel InjectionÐ3.0L Engine section of this group for system and component descriptions.

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 saves unnecessary test and diagnostic time. A thorough visual inspection includes the following checks:

(1)Check for correct spark plug cable routing. Ensure the cables are completely connected to the spark plugs and distributor.

(2)Check ignition coil electrical connections (Fig. 2).

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

(4)Verify vacuum connection at Purge Solenoid is secure and not leaking (Fig. 3).

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

(6)Check MAP sensor hose at MAP Sensor Assembly (Fig. 4), and at Vacuum Connection at Intake Plenum Fitting.

(7)Check alternator wiring connections. Ensure the accessory drive belt has proper tension.

14 - 118 FUEL SYSTEMS

Fig. 2 Ignition Coil Electrical Connection

Fig. 3 Electrical Connector Canister Purge Solenoid

Fig. 4 Map Sensor Electrical and Vacuum Connec-

tions

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

(9)Verify the engine ground strap is attached at the engine and dash panel (Fig. 6).

Ä

Fig. 5 Vapor Canister

Fig. 6 Oxygen Sensor Connector

(10)Ensure the heated oxygen sensor connector is connected to the harness connector (Fig. 6).

(11)Verify the distributor connector is connected to the harness connector (Fig. 7).

Fig. 7 Distributor Connector

Fig. 9 Oil Pressure Sending Unit Electrical Connec-

tion

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

10).

(17)Check throttle body electrical connections (Fig.

10).

(18)Check PCV hose connections (Fig. 11).

Fig. 12 EGR System Vacuum Hose Connections

(19)If equipped, check EGR system vacuum hose connections (Fig. 12).

(20)If equipped, check EGR tube to intake plenum connections (Fig. 12).

Fig. 13 Power Brake Booster and Speed Control

Vacuum Hose Connections (Without Anti-lock

Brakes)

Fig. 14 Speed Control Vacuum Hose Connection

(With Anti-lock Brakes)

(24)Inspect engine harness to main harness connections.

(25)Check all automatic transmission electrical connections (Fig. 15).

(26)Check the distance sensor electrical connection (Fig. 16).

(27)Inspect the engine controller 60-way electrical connector for damage or spread terminals. Verify the 60-way connector is fully inserted into the socket of the engine controller. Ensure wires are not stretched or pulled out of the connector (Figs. 17, 18, and 19).

Fig. 16 Distance Sensor Electrical Connector

Fig. 17 Engine ControllerÐAA Body

(28)Check the air conditioning, starter, ASD, fuel pump and radiator fan relay connections (Figs. 20, 21, and 22).

(29)Check battery cable connections.

(30)Check hose and electrical connections at fuel pump. Ensure connector is making contact with terminals on pump.