Resolving Power Loss in the Caterpillar B277 Compact Track Loader

[MikePhua]

The B277 and Caterpillar’s Compact Track Loader Expansion
The Caterpillar B277 was part of CAT’s early 2000s push into the compact track loader market, offering a blend of skid steer agility with the traction and flotation of a tracked undercarriage. Built for landscaping, construction, and utility work, the B277 featured a turbocharged diesel engine, high-flow hydraulics, and a sealed and pressurized cab. It was designed to compete with Bobcat’s T-series and Deere’s CTLs, and it quickly gained popularity in North America, with thousands sold through CAT’s dealer network.
Despite its robust design, the B277—like many compact machines—can suffer from intermittent power loss due to fuel delivery issues, especially as components age or contaminants enter the system.
Terminology Annotation
- Lift pump: A low-pressure fuel pump that transfers diesel from the tank to the injection system.
- Fuel water separator: A filter that removes water and particulates from diesel fuel before it reaches the engine.
- Pre-filter screen: A mesh screen located inside the lift pump or fuel inlet that traps large debris before it enters the filter.
- Suction line: The hose or pipe that draws fuel from the tank to the lift pump.
Symptoms and Initial Observations
Operators reported that the B277 would rev to full throttle for about ten seconds before sputtering and running rough. This occurred both under load and while stationary, suggesting a fuel delivery issue rather than a hydraulic or electronic fault. Air and fuel filters were replaced, but the problem persisted.
This behavior is typical of partial fuel starvation—where the engine receives enough fuel to start and rev briefly, but cannot sustain combustion under load due to restricted flow or air intrusion.
Investigating the Fuel System
The B277 may be equipped with either an electric or mechanical lift pump, depending on production year and engine variant. The electric pump is typically mounted on the right side of the engine and should activate when the key is turned on. If the pump fails to energize, fuel will not reach the injection system, leading to rough running or stalling.
For mechanical pumps, located on the left side of the engine, a small screw on top can be removed to access the internal pre-filter screen. This screen often traps debris such as:

• Plastic shavings from fuel tank liners
  
• Organic matter like leaves or algae
  
• Foreign objects introduced during refueling (e.g., sticks, cloth, trash bags)
  

One technician reported finding a sock lodged in the suction line, likely inserted as a prank or accidental contamination. When blowing out the lines with compressed air, a gurgling sound in the tank indicates that the obstruction has cleared.
Recommended Diagnostic Steps
To isolate the issue:

• Confirm pump operation by listening for activation at key-on
  
• Remove and inspect the pre-filter screen inside the lift pump
  
• Disconnect fuel lines and blow them out with compressed air
  
• Check for resistance or blockage in the suction line
  
• Inspect the fuel tank for floating debris or collapsed pickup tubes
  

If the pump fills the fuel filter during replacement, it is likely functioning. However, a partially blocked line or screen can still restrict flow enough to cause power loss.
Preventive Measures and Long-Term Solutions
To prevent future fuel delivery issues:

• Install a secondary inline filter upstream of the lift pump
  
• Use a tank strainer or screen to catch debris at the pickup point
  
• Flush the fuel tank annually, especially in dusty or humid environments
  
• Lock fuel caps to prevent tampering or accidental contamination
  
• Replace rubber fuel lines every 5–7 years to prevent internal delamination
  

In one case, a contractor began locking all fuel caps after discovering foreign objects in multiple machines. Since implementing this policy, no further incidents occurred.
Conclusion
Power loss in the Caterpillar B277 is often caused by fuel delivery restrictions—most commonly debris in the suction line or pre-filter screen. By methodically inspecting the pump, lines, and tank, operators can restore full engine performance and avoid costly downtime. In compact track loaders, where every ounce of torque matters, clean fuel flow is the foundation of reliable operation. With proper maintenance and vigilance, the B277 remains a powerful and dependable tool on any jobsite.