How to Fix No Fuel to Injectors on a Case 580B

[MikePhua]

Experiencing a Case 580B backhoe loader that suddenly dies and then refuses to send fuel to the injectors can be a complex and frustrating issue. Despite having fuel up to the fuel pump, if no fuel reaches the injector lines, the machine will fail to start or run. This detailed explanation breaks down the possible causes, diagnostic procedures, technical terminology, and practical solutions to help operators and technicians restore fuel delivery and engine performance efficiently.
Understanding the Case 580B Fuel System
The Case 580B fuel system involves several key components working together to ensure fuel reaches the engine cylinders:

• Fuel Tank and Petcock Valve: Stores diesel fuel; the petcock controls fuel flow from the tank and may have a protective screen that can become clogged.
  
• Fuel Lines: Transport fuel from the tank to the fuel pump and from the pump to the injectors.
  
• Fuel Filters: Remove debris and impurities to protect the injection system.
  
• Injection Pump (Roosa Master DBG 431 FCC46AJ): Pressurizes and distributes fuel to each injector; key for precise fuel timing and quantity.
  
• Injector Lines: High-pressure lines delivering fuel to individual engine cylinders.
  
• Return Line and Elbow: Return excess fuel from the injection system back to the tank.
  
• Bleeder Valve: Allows removal of air from the fuel system, essential for priming.
  

Terminology to Know:

• Injector Pump: Mechanical device that pressurizes and delivers fuel to the injectors.
  
• Bleeder Valve: A valve used to remove trapped air from fuel lines.
  
• Petcock Valve: A fuel shutoff valve located at the tank outlet.
  
• Fuel Return Line: Line returning unused fuel to the tank.
  
• Elbow Fitting: Connector in the return line that can become clogged or damaged.
  
• Fuel Filter Screen: Fine mesh screen that filters fuel entering the pump to prevent debris entry.
  
• Roosa Master Pump: A type of mechanical injection pump used on many Case machines.
  

Common Causes for No Fuel to Injectors Despite Fuel at Pump

• Clogged or Blocked Fuel Petcock Valve: The shutoff valve at the fuel tank often has a screen that can accumulate debris or rust, blocking fuel flow to the pump.
  
• Injection Pump Internal Failure: Worn or damaged pump components such as the governor weight retainer ring (flex ring), check valves, or seals can block fuel flow internally.
  
• Airlocks in Fuel System: Trapped air can prevent fuel flow; inadequate bleeding after repairs or leaks in fuel lines can cause this.
  
• Fuel Filter or Screen Blockage: Even if fuel is at the pump inlet, blockage in inline filters or screens inside the pump can prevent fuel delivery.
  
• Damaged or Misadjusted Injection Pump Timing: Incorrect timing or mechanical faults can stop fuel from being pumped out.
  
• Blocked Return Line or Elbow: If the fuel return path is blocked, it can affect fuel pressure and delivery.
  
• Worn or Cracked Fuel Lines: Leaks or cracks cause loss of fuel pressure and air ingress.
  
• Pump Not Rotating Properly: Failure of gear train or pump drive can prevent injection pump operation.
  

Step-by-Step Diagnostic and Troubleshooting Guide

1. Inspect the Fuel Petcock Valve at the Tank
   • Remove the petcock valve and check for plugged debris or rust on the screen.
     
   • Clean or replace the valve as needed to ensure free fuel flow.
     
2. Check Fuel Supply Lines and Filters
   • Inspect all fuel lines for cracks, kinks, or looseness.
     
   • Replace fuel filters and clean any inline screens.
     
   • Verify fuel flow at the pump inlet by disconnecting lines and observing fuel presence.
     
3. Bleed the Fuel System Thoroughly
   • Use bleeder valves on filters and pump to remove trapped air.
     
   • Pump the manual primer repeatedly until fuel flows without air bubbles.
     
   • Repeat bleeding after initial engine cranking to ensure air is fully purged.
     
4. Inspect Injector Lines and Return Line
   • Disconnect injector lines at the pump and check for fuel delivery when cranking.
     
   • Remove and inspect return line elbow for blockages; clean or replace if necessary.
     
5. Examine the Injection Pump Internals
   • If accessible, disassemble pump to check for broken governor weight retainer (flex ring), worn seals, or stuck check valves.
     
   • Ensure pump components move freely without binding.
     
   • Verify pump timing marks and adjust if necessary according to the service manual.
     
6. Check for Proper Pump Rotation
   • Confirm the injection pump gear/train is turning when cranking.
     
   • If not, inspect pump drive components for failure.
     
7. Test Fuel Pressure and Delivery
   • Use specialized gauges to measure fuel pressure at pump outlet.
     
   • Compare with manufacturer’s specifications for the Case 580B.
     

Practical Case Insights
One backhoe operator reported sudden stall and no fuel delivery to injectors despite seeing fuel at the pump inlet. Removing and cleaning the petcock valve screen restored fuel flow, confirming the screen had blocked fuel supply. Another common scenario involves worn internal pump components causing interrupted fuel delivery, requiring rebuild or replacement of the Roosa Master pump.
Additional Recommendations

• Always use genuine or high-quality replacement parts for fuel system components.
  
• Maintain cleanliness during fuel pump servicing to prevent introducing contaminants.
  
• Keep a spare fuel filter and petcock valve on hand for quick replacement.
  
• Perform regular inspection and maintenance of fuel system to avoid unexpected failures.
  
• Consult detailed service manuals for pump rebuilding and timing procedures.
  
• Use proper tools and safety precautions during fuel system work to prevent fire hazards.
  

Summary List: Key Checks for Case 580B No Fuel to Injectors Issue

• Remove and clean petcock valve screen at fuel tank
  
• Inspect and replace fuel filters and lines as needed
  
• Bleed fuel system completely to remove airlocks
  
• Check injector lines for fuel delivery during cranking
  
• Inspect and clear blockage in fuel return line and elbow
  
• Disassemble fuel pump to inspect internal components (flex ring, check valves, seals)
  
• Verify injection pump timing and adjust if required
  
• Confirm fuel pump gear drive operation
  
• Test fuel pressure at pump outlet against specifications
  
• Maintain clean fuel and system during servicing for longevity
  

Conclusion
No fuel delivery to the injectors on a Case 580B, despite having fuel at the pump, is often caused by a blocked petcock screen, internal injection pump failures, airlocks, or fuel system blockages. Systematic inspection starting from the tank petcock to fuel lines and pump internals, along with thorough bleeding and timing checks, is essential to restore proper fuel flow and engine function. Practical experience shows that regular maintenance, careful cleaning, and correct pump servicing prevent many such fuel issues, ensuring reliable machine operation.