ARMY TM 9-281-252-24 AIR FORCE TO 38G1-92-2 TABLE 3-2.  Troubleshooting Malfunction Test or Inspection Corrective Action a. Check fuel system for leaks.  If not leaks, do step 2. b. Repair fuel system. Step 2. Check for blocked air intake system. Remove blockage as found.  If no blockage is found, do step 3, refer to end item technical manual. Step 3. Check for defective fuel injectors. a. Remove and test fuel injectors.  Refer to paragraph 3-17.  If not defective, do step 4. b. Replace fuel injector(s).  Refer to paragraph 3-17. Step 4. Check for loss in vacuum. a. Perform vacuum check.  Refer to paragraph 3-5.2. b. If not loss in vacuum, do step 5. Step 5. Check for improper fuel pump timing. a. If timing is correct, do step 6. b. Adjust fuel pump timing.  Refer to paragraph 3-14. Step 6. Defective fuel injection pumps. a. Test fuel injection pumps.  Refer to paragraph 3-13.3. b. Replace fuel injection pump(s).  Refer to paragraph 3-13. 11.  BLACK OR GRAY SMOKE. Step 1. Check for defective fuel injectors. 3-8