ARMY TM 9-6115-670-14&P 4-12 2. ENGINE CRANKS BUT FAILS TO START. STEP 1. Check for clogged or dirty fuel filter. a.  If the fuel filter is clogged or dirty, SERVICE fuel filter (para 4.30.). b.  If the fuel filter is clean, proceed to step 2. STEP 2. Check for obstructions, cracks or leaks in fuel supply lines. a.  If fuel lines are clogged, cracked, or leaking, replace fuel lines (para 4.35.). b.  If fuel lines are free of obstructions, cracks or leaks, proceed to step 3. STEP 3. Check for air in fuel system. a.  Tighten any loose fuel lines and bleed the fuel system. b.  If the APU does not start, proceed to step 4. STEP 4. Check for proper installation and operation of glow plugs. a.  If the glow plugs are improperly installed, non operational, or defective, reinstall, REPAIR or REPLACE as required. b.  If the glow plugs are functioning properly, proceed to step 5. STEP 5. Check fuel filter sediment container for water or other contaminants in the fuel, incorrect grade or fuel type. a.  If the fuel is contaminated, drain entire fuel system including vehicle fuel tank and APU day tank (para 4.32. or 4.33.). b.  Replace fuel filter (para 4.30.) and service with clean fuel. c.  Bleed fuel system. d.  If the fuel is uncontaminated, proceed to step 6. STEP 6. Check for fuel leaks at injection pipes. a.  If fuel is leaking from injection pipes, stop the leak by tightening the retaining nuts or replacing the fuel injection lines. b.  If fuel is not leaking from the injection pipe lines, proceed to step 7. STEP 7. Check for compression leak from cylinder. a.  If a compression leak exists from a loose injection nozzle, tighten injection nozzle to proper torque value. b.  If the injection nozzle is tight, proceed to step 8. STEP 8. Check for defective fuel transfer pump. a.  If fuel transfer pump is defective, REPLACE fuel transfer pump (para 4.31.). b.  If fuel transfer pump functions properly, proceed to step 9.