John Deere 550H Dozer Intermittent Starting Problem

[MikePhua]

Overview of Common Starting Issues
A dozer such as the 2004 John Deere 550H that cranks (turns over) but intermittently will not start commonly suffers from issues related to the fuel delivery system, electrical connections, or control solenoids. In the provided case, the machine ran for several hours after initially refusing to start, only to repeat the no-start condition later, suggesting an intermittent electrical or fuel supply issue over outright mechanical failure.
Technical Analysis of Fault Pathways
Typically for diesel engines, three key systems must function for the engine to start:

• Fuel supply (including injector solenoids and relays)
  
• Electrical system (battery, fuses, relays, solenoid wiring, ignition connections)
  
• Air intake/exhaust, which is less often a culprit unless there’s blockage
  

In many cases, a no-start with the engine cranking points to either the fuel is not reaching the injectors or a loss of electrical activation to components like fuel shutoff solenoids. Electrical faults—such as broken, corroded, or loose wires, failing relays, or a weak ground—are high-probability culprits, especially if the failure is not constant but sporadic.
Step-by-Step Troubleshooting Guidance

• Check Fuel Supply Chain:
  • Ensure the fuel shutoff valve is ON and fuel level is adequate.
    
  • Inspect for clogged filters, collapsed lines, or air bubbles in lines which can cause sporadic fuel delivery.
    
  • If possible, watch for fuel at injector lines when cranking.
    
• Examine Electrical Pathways:
  • Confirm battery terminal connections are tight, clean and corrosion-free.
    
  • Trace the wiring to the fuel solenoid and check for damaged insulation or worn plugs.
    
  • Test solenoid power with a multimeter while someone turns the key to “start.”
    
  • Inspect fuse boxes for blown fuses and related relays, including those not on the primary fuse block.
    
• Look for Safety Interlocks:
  • Ensure the machine is neutral, all required conditions (seat switch, parking brake) are met so interlocks allow starting.
    
  • Look for failing neutral switches or other safety components.
    

Field Examples and Case Studies
Operators sometimes report that intermittent connection problems resolved simply by re-seating or cleaning battery and solenoid terminals. Persistent, hard-to-trace electrical gremlins are often caused by moisture or vibration loosening connections over time, or by a failed relay that works intermittently before final failure.
In one notable case, repeated no-starts on a John Deere tractor were ultimately traced to a corroded inline fuse tucked in the main harness, which would pass current some days and not others. Another example involved a cracked fuel line allowing air to enter the system intermittently.
Terminology Explained

• Fuel Shutoff Solenoid: An electrically controlled valve that allows or blocks fuel flow to the injectors.
  
• Relay: An electrically actuated switch often used to transmit power to solenoids or control circuits.
  
• Neutral Switch: A safety device that only allows starting when the transmission is in neutral.
  

Suggestions for a Working Practice

• Always troubleshoot intermittent issues by jiggling wires and connectors while attempting a start, to see if something loose is the cause.
  
• Keep a can of starting fluid to test for air/fuel delivery, but only after confirming it's safe for your equipment type.
  
• Carry a multimeter for checking live voltage at likely failure points such as fuse panels and solenoid connectors.
  

John Deere 550H Background
John Deere’s 550H mid-sized dozer, part of a renowned line dating back to the 20th century, is famous for electrical and fuel system reliability—but just like all field machines, is susceptible to faults from time, corrosion, and vibration. Companies like John Deere have sold hundreds of thousands of such machines, supported by a global network of parts and technical documentation.
Conclusion
An intermittent no-start issue on a John Deere 550H dozer is almost always an electrical contact, solenoid relay, or fuel supply problem. Systematic checks of battery, fuses, and all connections—combined with occasional troubleshooting of relays and wiring—can usually resolve the issue without resorting to expensive expert intervention. Regular inspection and timely replacement of suspect components are the surest way to reliable field starts.