Checking the Basics

VISUAL INSPECTION
A visual inspection for loose, disconnected, or incorrectly routed wires and hoses should be made. This should be done before attempting to diagnose or service the fuel injection system. A visual check will help spot these faults and save unnecessary test and diagnostic time. A thorough visual inspection will include the following checks:

Powertrain Control Module:

1. Verify that the 60-way connector is fully inserted into the connector of the Powertrain Control Module (PCM). Verify that the connector mounting screw is tightened to 4 N-m (35 in. lbs.) torque.
2. Inspect the battery cable connections. Be sure that they are clean and tight.
3. Inspect fuel pump relay and air conditioning compressor clutch relay (if equipped). Inspect the Automatic Shutdown (ASD) relay connections. Inspect starter motor relay connections. Inspect relays for signs of physical damage and corrosion.

Ignition Coil Location:

4. Inspect ignition coil connections. Verify that coil secondary cable(s) are firmly connected to coil.
5. Be sure that spark plug cables are firmly connected to the coil and the spark plugs are in their correct firing order. Inspect spark plug condition. Connect vehicle to an oscilloscope and inspect spark events for fouled or damaged spark plugs or cables.
6. Verify that generator output wire, generator connector and ground wire are firmly connected to the generator.
7. Inspect the system body grounds for loose or dirty connections.
8. Verify firm connections at PCV valve and hose.
9. Verify that the fuel line, vacuum hose and electrical connector are firmly connected to the fuel pump module.

Fuel Rail Mounting:

10. Inspect fuel line quick-connect fitting-to-fuel rail connection. The fuel line-to-fuel rail connection is made at the rear of the engine.
11. Verify that hose connections to all ports of vacuum fittings on intake manifold are tight and not leaking.
12. Inspect accelerator cable, transmission throttle cable (if equipped) and cruise control cable connections (if equipped). Check their connections to the throttle arm of throttle body for any binding or restrictions.
13. If equipped with vacuum brake booster, verify that vacuum booster hose is firmly connected to fitting on intake manifold. Also check connection to brake vacuum booster.
14. Inspect the air cleaner inlet and air filter element for dirt or restrictions.
15. Inspect radiator grille area, radiator fins and air conditioning condenser for restrictions.

Intake Manifold Air Temperature Sensor:

16. Verify that the intake manifold air temperature sensor wire connector is firmly connected to harness connector.

Throttle Body Connector Locations:

17. Verify that manifold absolute pressure (MAP) sensor electrical connector is firmly connected to MAP sensor.
18. Verify that fuel injector wire harness connectors are firmly connected to injectors in the correct order. Each harness connector is numerically tagged with the injector number (INJ 1, INJ 2 etc.) of its corresponding fuel injector and cylinder number.
19. Verify harness connectors are firmly connected to idle air control (IAC) motor, throttle position sensor (TPS) and MAP sensor.

Coolant Temperature Sensor Location:

20. Verify that wire harness connector is firmly connected to the engine coolant temperature sensor.
21. Raise and support the vehicle.
22. Verify that oxygen sensor wire connectors are firmly connected to the sensors. Inspect sensors and connectors for damage.
23. Inspect for pinched or leaking fuel lines/tubes. Inspect for pinched, cracked or leaking fuel hoses.
24. Inspect for exhaust system restrictions such as pinched exhaust pipes, collapsed muffler or plugged catalytic convertor.
25. If equipped with automatic transmission, verify that electrical harness is firmly connected to park/neutral switch.

Vehicle Speed Sensor Location:

26. Verify that the harness connector is firmly connected to the vehicle speed sensor.
27. Verify that electric fuel pump/gauge sender unit wire connector is firmly connected to harness connector.
28. Inspect fuel hoses at fuel pump/gauge sender unit for cracks or leaks.
29. Inspect transmission torque convertor housing (automatic transmission) or clutch housing (manual transmission) for damage to timing ring on drive plate/flywheel.
30. Verify that battery cable and solenoid feed wire connections to the starter solenoid are tight and clean. Inspect for chaffed wires or wires rubbing up against other components.