Initial Inspection and Diagnostic Overview

A visual inspection for loose, disconnected, or improperly routed wires and hoses should be made before attempting to diagnose the fuel injection system. A visual check will help locate these faults and save unnecessary diagnostic time.

1. Check battery cable connections for tightness. The battery should be free of dirt & corrosion. Check color of test indicator on top of battery.
2. Check engine control system ground connections on side of frame rail between battery and air cleaner. They should be free of corrosion.
3. Check engine control system relays connections. Check relays for signs of physical damage and corrosion.
4. Check air cleaner pre-heat hose for rips & tears. Replace damaged hoses. Ensure that the hose is connected properly. Check air cleaner element. If dirty, replace.
5. Check accelerator & cruise control cables for binding. Repair as necessary.
6. Remove the accelerator and cruise control cables. Check operation of the throttle return springs. Replace the spring if it is weak.
7. Inspect the Idle Speed Regulator inlet & outlet hoses for fatigue.
8. Check that the electric cooling fan switch connector is connected to the switch. Inspect for corrosion.
9. Check the air cleaner ambient air opening for blockage. Ensure that the TAC vacuum motor is connected to the motor.
10. Check the Crankcase Ventilation (CCV) hoses. Replace if damaged.
11. Check the EGR valve solenoid. Ensure that the vacuum tubes are connected to the solenoid and are not damaged. Inspect the wire connector for corrosion.
12. Check coolant temperature sensor for scuffed or exposed wires or corrosion.
13. Check EGR valve and transducer for damage. Inspect all vacuum hoses for fatigue or damage.
14. Check the EGR tube for restrictions or leaks.
15. Check oxygen sensor electrical connections for damage or corrosion.
16. Check vacuum brake booster hose for damage and tightness.
17. Check Manifold Absolute Pressure (MAP) sensor vacuum tube for damage. Check connection for corrosion. Check sensor wires for damage.
18. Check harness, connector to connector on dash for damage. Check tightness of mounting bolt.
19. Check speed sensor & connections for damage.
20. Check fuel injector & connectors for damage & tightness.
21. Check that the thermal vacuum (TVS) supply tube and the TVS to vacuum tube are connected to the thermal vacuum switch (TVS) in the air cleaner cover.
22. Check Throttle Position Sensor & connectors & wiring for damage.
23. Check the body to engine ground strap and the ground strap connections for damage & tight connections.
24. Check knock sensor & connector for damage.
25. Verify that distributor cap is attached to distributor, that plug wires are connected to cap & to plugs in correct firing order. Check that coil wire is connected to cap and to coil. Check for corrosion.
26. Check ignition module & coil assembly connections for damage. Check that connectors are completely engaged with module.
27. Check vacuum reservoir & tubes for tightness & damage. Verify that the cruise control servo vacuum supply tube is connected to the servo.
28. Check the two terminal connectors & output wires are connected to the alternator & check for signs of arcing & corrosion.
29. Check starter connections for corrosion. Check battery cable & solenoid wires for damage.
30. Check fuel guage sending unit & pump electrical connectors for corrosion & damage. Inspect for fuel leaks.
31. Check for collapsed exhaust pipe or muffler.