TM  10-3930-643-34 ENGINE,  FUEL,  EXHAUST  AND  COOLING  TROUBLESHOOTING  AND  MAINTENANCE.  (cont) 4-1. Engine, Fuel, Exhaust and Cooling Troubleshooting. (cont) MALFUNCTION TEST  OR  INSPECTION CORRECTIVE  ACTION C. ENGINE MISFIRES, IS ERRATIC OR VISUAL SMOKE FROM EXHAUST. Step 1. Test for damaged fuel injector nozzles or low nozzle valve opening  pressure,  refer  to  paragraph  4-12. If fuel injectors are satisfactory, proceed to step 2. Step 2. Check  for  proper  fuel  injection  pump  timing,  refer  to  paragraph 4-14. If timing is correct, proceed to step 3. Step 3. Check for proper valve lash adjustment, refer to paragraph 4-6. If valve lash adjustment and fuel injection pump timing are correct, proceed to step 4. Step  4.  Test  for  proper  engine  cylinder  compression  (335-365  psi), refer to paragraph 4-1.i. If compression does not meet specifications, check for proper valve adjustment,  refer  to  paragraph  4-6. If valves are properly adjusted, check for worn valves and/or valve seats or a blown cylinder head gasket, refer to paragraph 4-4. 4-4