ARMY TM 9-2815-257-24 AIR FORCE TO 38G1-128-2 MARINE CORPS TM 10155A/2815-24/3 3-12 Table 3-2.  Unit Level Troubleshooting (continued) MALFUNCTION TEST OR INSPECTION CORRECTIVE ACTION 8. ENGINE EMITS BLACK SMOKE a.     Check for clogged or dirty air filter. Remove and replace air filter (Para. 3-16). b.    Check for clogged, sticking, or worn fuel injector nozzle. Remove and replace fuel injector (Para. 3-14). c. Refer trouble to direct support maintenance level.