Case 1845B Auxiliary Fuel Pump Troubles and Solutions

[MikePhua]

Background of the Case 1845B Skid Steer
The Case 1845B skid steer loader was one of the most widely used machines in the late 1970s through the 1990s. Known for its durability and versatility, the 1845B became a benchmark in the construction and agricultural industries. Case Corporation, which later became part of CNH Industrial, built the model to compete with Bobcat and other emerging skid steer manufacturers. The 1845B was powered by a Case diesel engine with mechanical fuel injection, a simple yet reliable system that allowed operators to work in harsh environments with minimal electronics. Sales of the 1845B were strong across North America and Europe, with thousands of units produced, many of which are still in operation today due to their rugged design and easy-to-service components.
Function of the Auxiliary Fuel Pump
The auxiliary fuel pump, often referred to as the lift pump, plays a critical role in supplying diesel from the fuel tank to the injection pump. In mechanical diesel engines like those found in the Case 1845B, the lift pump ensures constant pressure and flow so that the injection pump can deliver precise fuel amounts to the engine cylinders. When this pump fails, the engine may crank but not start, or it may run erratically due to inconsistent fuel supply.
Common Symptoms of Pump Failure
Operators have reported several typical symptoms that indicate a failing lift pump in the 1845B:

• The machine cranks but does not fire.
  
• Loss of power under heavy load.
  
• Engine stalling after a short period of operation.
  
• Presence of air bubbles in the fuel line.
  
• Difficulty priming the fuel system after filter replacement.
  

These issues often appear gradually, making diagnosis challenging without proper inspection.
Diagnostic Steps
To identify whether the auxiliary fuel pump is the culprit, operators and mechanics can take several steps:

1. Check for Fuel Flow – Disconnect the line between the pump and the injection pump to verify whether diesel is being pushed consistently.
   
2. Inspect for Air Leaks – Examine hoses, clamps, and fittings for cracks or loose connections that could introduce air into the system.
   
3. Test Pump Pressure – The Case 1845B’s lift pump should deliver between 4–7 psi. Using a simple pressure gauge can confirm pump health.
   
4. Bypass Test – Installing a temporary electric pump can verify if the machine runs properly when bypassing the mechanical pump.
   

Replacement Options
When the auxiliary pump is found to be defective, operators have two main options:

• Mechanical OEM-style pump – This preserves originality and requires no wiring modifications.
  
• Electric aftermarket pump – Often preferred for ease of priming and reliability. A low-pressure electric pump rated at 5–7 psi is commonly used as a replacement.
  

While the mechanical pump is robust, the electric alternative provides consistent pressure and makes cold starting easier. However, electrical reliability and proper installation must be considered to avoid new problems.
Preventive Maintenance
To extend the life of the fuel system in the Case 1845B, operators should follow best practices:

• Replace fuel filters every 250 hours of operation.
  
• Keep the fuel tank clean and use diesel stabilizer to prevent microbial growth.
  
• Regularly inspect hoses and clamps for deterioration.
  
• Drain water separators to avoid corrosion in the injection pump.
  

Real-World Example
A small contractor in Illinois reported repeated starting issues with their 1845B during winter. After struggling with mechanical lift pump failures, they replaced the system with an electric low-pressure pump. This not only eliminated the hard-starting problem but also reduced downtime, allowing the machine to continue operating through the cold season.
Conclusion
The Case 1845B skid steer remains a classic workhorse in construction and agriculture, but like any diesel-powered equipment, its auxiliary fuel pump can be a point of failure after decades of service. Understanding the role of the pump, recognizing failure symptoms, and choosing between mechanical and electric replacements can keep these machines running reliably. For many owners, investing in an electric conversion has become a practical solution, ensuring that a machine built over thirty years ago can still compete on today’s job sites.