TM 10-3930-638-24&P 2-9.  ENGINE  TROUBLESHOOTING  (cont) MALFUNCTION TEST  OR  INSPECTION CORRECTIVE   ACTION 3.  ENGINE  STARTS  BUT  WILL  NOT  RUN  (cont) Step 7. (cont) (1) If fuel is pumped through injection pump, proceed to step 8. (2) If fuel is not pumped through fuel injection pump, replace it (notify direct support maintenance). b. If +24 Vdc is not obtained, troubleshoot electrical system (para 2-19). c. If fuel is pumped out of disconnected fuel line, proceed to step 8 below. Step 8. Check for fuel leaks at fuel injector lines. a. If fuel leaks are observed, tighten or replace lines (para 3-6a; notify direct support mainte- nance) b. If fuel lines are okay, proceed to step 9 below. Step 9. Remove radiator cap, start engine, and observe coolant for gas bubbles. If gas bubbles rising in coolant are observed, replace cylinder head gasket (para 3–5g; notify direct  support  maintenance). 4.  ENGINE  MISFIRES Step 1. Check for incorrect or contaminated fuel in fuel tank (if contaminated, fuel will have a  milky  white  appearance). a. If fuel is contaminated, drain fuel tank, clean and fill with correct fuel (para 2– 15d (1)) and replace fuel filters (para 2–15e and 2–1 5f). b. If fuel is not contaminated, proceed to step 2 below. Step 2. Operate engine for 15 minutes at idle speed. Carefully and slowly remove radiator cap. Check coolant temperature using a thermometer be sure that thermometer does not touch any metal parts of radiator. Coolant  temperature  shall  be  between  175  to  200  degrees  F. a. If coolant temperature is not between 175 to 200 degrees F, remove and test thermostat. b. If coolant temperature is between 175 to 200 degrees F, proceed to step 3 below. Step 3. Check for fuel leaks at fuel injector lines. a. If fuel leaks are observed, tighten or replace lines (para 3-6a; notify direct support mainte- nance) b. If fuel lines are okay, proceed to step 4 below. 2-17