Engine Hard to Start / Fails to Start

Step 1: Check the Fuel System

• Possible causes:

  • Empty or contaminated fuel tank

  • Blocked fuel filter

  • Air trapped in fuel lines

  • Weak or faulty fuel pump / injectors

• Solutions:

  • Refill with clean, high-quality diesel

  • Replace fuel filter

  • Bleed the fuel system to remove air

  • Test and repair/replace pump or injectors

Step 2: Check the Battery & Electrical System

• Possible causes:

  • Weak or dead battery

  • Loose or corroded battery terminals

  • Starter motor failure

  • Faulty alternator (not charging battery)

• Solutions:

  • Recharge or replace the battery

  • Clean and tighten terminals

  • Test starter motor and replace if needed

  • Check alternator output

Step 3: Check the Air Intake System

• Possible causes:

  • Air filter clogged

  • Intake hoses damaged or blocked

  • Turbocharger malfunction (if equipped)

• Solutions:

  • Clean or replace the air filter

  • Inspect intake piping for cracks or blockages

  • Check turbocharger condition

Step 4: Check the Engine Compression

• Possible causes:

  • Worn piston rings

  • Valve leakage

  • Cylinder head gasket failure

• Solutions:

  • Perform a compression test

  • Repair valves, piston rings, or gasket as needed

Step 5: Check Sensors & ECU (Modern Excavators)

• Possible causes:

  • Faulty temperature, pressure, or crankshaft sensor

  • ECU malfunction

• Solutions:

  • Scan error codes with diagnostic tool

  • Replace faulty sensor

  • Reprogram or replace ECU if needed

Quick Tip for Mechanics:

• Always start with the simplest checks: fuel, battery, filters.

• Record symptoms (e.g., “engine cranks but no fire” vs. “engine doesn’t crank at all”).

• Use diagnostic tools when available to save time.