TM 10-3930-669-20 7.  ENGINE RUNS ROUGH OR MISFIRES (CONT). KNOWN INFO Fuel OK. POSSIBLE PROBLEMS Fuel lines loose or damaged. Intake/exhaust valve adjustment incorrect. Air in fuel lines. Fuel injector(s) faulty. KNOWN INFO Fuel OK. Fuel lines OK. POSSIBLE PROBLEMS Intake/exhaust valve adjustment incorrect. Air in fuel lines. Fuel injector(s) faulty. TEST OPTIONS Visual inspection. REASON FOR QUESTION If fuel lines are damaged or leaking, engine will run rough. TEST OPTIONS Audible inspection. REASON FOR QUESTION If air is trapped in fuel system, engine will run rough. 2-94