Preliminary Inspection

General Information

Fuel system diagnosis should begin with a preliminary inspection followed by a road test to confirm existence of a problem.

Preliminary inspection consists of visual checks designed to rule out faults caused by leaks, fuel line damage, or loose electrical connections.

Preliminary Inspection

1. Check fuel gauge readings for main and auxiliary tanks.
2. Visually inspect fuel lines at tanks, selector valve, fuel pump, and at engine. Look for loose, damaged, leaking lines.
3. Check vacuum actuator hose on turbo diesel models.
4. Check wiring for fuel lift pump.
5. Check glow plug and relay wiring. Also check electronic accelerator pedal wiring on turbo diesel. Look for loose connections at all points (including battery), or for damaged, pinched wires.
6. Check serpentine drive belt tension and condition.
7. Note if any indicator lights are on. If engine runs, also check voltage, oil pressure, and coolant temperature readings.
8 Check exhaust system components for damage, loose joint connections, or grounding against body.
9. Inspect transmission linkage and wiring connections, especially if vehicle is used for off road operation.
10. If vehicle is drivable, and no obvious problems are found, road test vehicle. If vehicle is not drivable, refer diagnosis charts and scan tool diagnosis.