Troubleshooting a Doosan P185 Air Compressor That Cranks but Won’t Start

[MikePhua]

The Doosan P185 is a widely used portable air compressor, known for its durability and reliability in various construction and industrial applications. However, like any mechanical equipment, it can encounter issues that hinder its performance. One common problem reported by operators is the engine cranking without starting. This situation can be frustrating, especially when the compressor is needed for critical tasks.
Understanding the Doosan P185
The Doosan P185 is a Tier 4 Final-compliant portable air compressor, typically powered by a Doosan D24 engine. It delivers 185 cubic feet per minute (CFM) of compressed air at a maximum pressure of 125 psi. The compressor is equipped with features like FlexAir technology, allowing operators to adjust air pressure from 100 to 150 psi via the control panel. Despite its robust design, the P185 is not immune to starting issues.
Common Causes of Cranking Without Starting
Several factors can contribute to a Doosan P185 engine cranking without starting:

1. Fuel System Issues: Problems such as clogged fuel filters, air in the fuel lines, or a malfunctioning fuel shut-off solenoid can prevent the engine from receiving adequate fuel.
   
2. Electrical System Problems: Faulty fuses, corroded battery terminals, or issues with the ignition switch can disrupt the starting circuit.
   
3. Engine Control Module (ECM) Faults: The ECM manages engine functions and can inhibit starting if it detects faults or malfunctions.
   
4. Glow Plug Malfunctions: In cold weather, faulty glow plugs can prevent proper engine ignition.
   
5. Starter Motor or Relay Failures: A worn-out starter motor or a defective relay can cause cranking without starting.
   

Diagnostic Steps
To identify and resolve the issue, follow these diagnostic steps:

1. Check Fuel Supply: Ensure there is clean, adequate fuel in the tank. Inspect fuel filters for clogs and replace them if necessary. Bleed the fuel system to remove any air pockets.
   
2. Inspect Electrical Components: Examine battery terminals for corrosion and ensure they are tightly connected. Check all relevant fuses and replace any that are blown. Test the ignition switch and wiring for continuity.
   
3. Assess the ECM: Use diagnostic tools to check for any fault codes stored in the ECM. Address any identified issues accordingly.
   
4. Test Glow Plugs: In cold conditions, verify that glow plugs are functioning correctly. Replace any faulty plugs.
   
5. Examine Starter System: Listen for unusual sounds during cranking. If the starter motor sounds weak or inconsistent, it may need replacement. Test the starter relay for proper operation.
   

Preventive Maintenance Tips
To minimize the risk of starting issues:

• Regularly Replace Fuel Filters: Clogged filters can restrict fuel flow and cause starting problems.
  
• Maintain Clean Battery Terminals: Corrosion can impede electrical flow, leading to starting failures.
  
• Perform Routine Electrical Inspections: Regularly check wiring and connections for wear or damage.
  
• Monitor Engine Performance: Address any unusual engine behavior promptly to prevent further issues.
  

Conclusion
A Doosan P185 air compressor that cranks but won't start can be attributed to various factors, including fuel system issues, electrical problems, ECM faults, glow plug malfunctions, or starter system failures. By systematically diagnosing and addressing these potential causes, operators can restore the compressor to full functionality. Regular maintenance and timely repairs are essential to ensure the longevity and reliability of the Doosan P185.