Symptom Related Diagnostic Procedures

ENGINE CRANKS BUT WILL NOT START

1. No fuel in tank.
2. Triggered inertia switch.
3. Clogged fuel filter(s).
4. Inoperative fuel pump.
5. Inoperative air bypass valve.
6. Dirt, rust or water contamination in lines.

LACK OF POWER

1. Low fuel pump pressure.
2. Blocked or sticking fuel injectors.
3. Inoperative fuel pressure regulator.
4. Inoperative boost control solenoid.
5. Clogged fuel filter(s).

ROUGH ENGINE IDLE

1. Incorrect curb idle speed.
2. Inoperative fuel injector(s).
3. Air or vacuum leakage.
4. Inoperative air bypass valve.

ENGINE DIESELS OR IDLES FAST

1. Incorrect idle speed.
2. Air or vacuum leakage.

SPARK KNOCKING/PINGING

1. Improper fuel.

EXCESSIVE EXHAUST SMOKE

1. Black smoke.
a. Restricted air cleaner element.
b. EEC components.