Diagnosing Fuel Delivery Problems on a Bobcat 773 Skid Steer

[MikePhua]

Fuel starvation in a Bobcat 773 is often caused by a clogged pickup tube, blocked fuel line, or malfunctioning hand primer pump. These issues can mimic injector or pump failure but are usually resolved with targeted cleaning and inspection.
Bobcat 773 background and fuel system layout
The Bobcat 773 was introduced in the late 1990s as a mid-size skid steer loader designed for construction, landscaping, and agricultural use. It features:

• A Kubota V2203 diesel engine
  
• Mechanical fuel injection system
  
• Hand primer pump for manual fuel priming
  
• Fuel tank with internal pickup tube and check ball
  
• Inline fuel filter and water separator
  

Bobcat, founded in 1947 and now part of Doosan Group, has sold tens of thousands of 773 units globally. The machine is known for its reliability, but fuel system issues can arise after years of use, especially in dusty or wet environments.
Common symptoms of fuel delivery failure
Operators have reported:

• Engine cranks but fails to start
  
• Hand primer pump feels dry or offers no resistance
  
• Fuel filter remains empty after priming
  
• Blowing air into the fuel line fails to reach the tank
  

These symptoms suggest a blockage in the fuel pickup system, not a failure of the injection pump or injectors.
Pickup tube and check ball obstruction
Inside the fuel tank, the pickup tube includes a small check ball designed to prevent backflow. Over time, debris such as rust flakes, algae, or sediment can clog the elbow where the tube exits the tank. This prevents fuel from reaching the primer pump and filter.
To diagnose:

• Disconnect the fuel line at the primer pump
  
• Attempt to blow air back toward the tank
  
• If resistance is felt, the pickup tube or check ball is likely blocked
  

Some technicians recommend removing the pickup tube entirely and inspecting the elbow for debris. In severe cases, the check ball may be removed or replaced with a screen-type pickup.
Hand primer pump and filter inspection
If the pickup tube is clear but fuel still fails to reach the filter:

• Inspect the hand primer pump for internal seal failure
  
• Replace the inline fuel filter and check for water contamination
  
• Ensure all hose clamps are tight and free of air leaks
  

One operator in Alberta noted that his 773 wouldn’t prime after sitting for a month. After replacing the primer pump and cleaning the pickup elbow, the machine started immediately.
Preventive maintenance and fuel care

• Drain and clean the fuel tank every 1,000 hours
  
• Replace fuel filters every 250 hours or seasonally
  
• Use biocide additives to prevent algae growth in diesel
  
• Store fuel in sealed containers away from moisture
  
• Inspect primer pump annually for seal wear
  

In cold climates, gelled fuel can also block the pickup tube. Using winter-grade diesel and anti-gel additives helps prevent this.
Conclusion
Fuel delivery issues in a Bobcat 773 are often caused by pickup tube blockage or primer pump failure. These problems can be resolved without major disassembly if diagnosed correctly. Regular fuel system maintenance and tank cleaning are essential to prevent recurrence and ensure reliable engine starts.