The Fuel Sensor Problem in Bobcat 773 G-Series

[MikePhua]

Background of the Bobcat 773 Skid Steer
The Bobcat 773 skid steer loader belongs to the G-Series, a generation of compact equipment that gained popularity in the late 1990s and early 2000s. Manufactured by Bobcat Company, a subsidiary of Doosan Group since 2007, the 773 model was designed for versatility in construction, landscaping, and agricultural tasks. With a rated operating capacity of around 1,750 lbs and a turbocharged diesel engine producing approximately 46 horsepower, the 773 offered a balance of power and maneuverability. By the mid-2000s, Bobcat had sold hundreds of thousands of skid steers globally, with the 773 being one of the most widely adopted models in North America.
Understanding the Fuel Sensor System
The fuel sensor in the Bobcat 773 is part of the fuel level monitoring system, which includes a float mechanism inside the fuel tank, a sending unit, and a dashboard gauge. The float rises and falls with the fuel level, transmitting resistance values to the gauge via the sending unit. This resistance is converted into a readable fuel level. In technical terms, the sending unit operates on a variable resistor principle, often referred to as a potentiometric sensor.
Common Symptoms and Diagnostic Clues
Owners of the 773 G-Series have reported persistent issues where the fuel gauge reads empty despite a full tank. This symptom typically points to one of the following:

• Faulty sending unit: The float may be stuck or the resistor worn out.
  
• Disconnected or corroded wiring: Electrical continuity is essential for accurate readings.
  
• Dashboard gauge malfunction: Less common, but possible if the display unit fails.
  

In one case from Brooklyn, New York, a contractor noticed the gauge always showed empty, leading to unnecessary refueling and downtime. After checking the manual and inspecting the tank, he found no clear instructions on accessing the sensor.
Accessing the Fuel Tank and Sensor
To reach the fuel sensor in the Bobcat 773 G-Series, the operator must first remove the rear engine access panel. The fuel tank is mounted beneath the loader arms and adjacent to the hydraulic reservoir. Accessing the sending unit requires:

• Disconnecting the battery to prevent electrical shorts.
  
• Removing the protective shroud over the tank.
  
• Locating the sensor port, typically sealed with a circular flange and screws.
  
• Extracting the sending unit carefully to avoid damaging the float arm.
  

Replacement parts are available through authorized Bobcat dealerships, though aftermarket options exist. The OEM part number may vary slightly depending on production year, so verifying with the serial number is recommended.
Preventive Maintenance and Sensor Longevity
To extend the life of the fuel sensor:

• Use clean diesel fuel and avoid contamination.
  
• Periodically inspect wiring harnesses for wear or corrosion.
  
• Avoid overfilling the tank, which can stress the float mechanism.
  

Technicians suggest checking sensor resistance with a multimeter. A healthy unit should show resistance changes as the float moves. If the reading remains static, the sensor is likely defective.
Anecdotes and Industry Trends
In 2010, a fleet operator in Ohio retrofitted his Bobcat 773s with digital fuel monitoring systems after repeated sensor failures. This move reduced fuel theft and improved maintenance scheduling. By 2015, smart sensors with Bluetooth connectivity began appearing in newer models, though retrofitting older machines remained a challenge.
In a related news story from 2023, a construction firm in Alberta faced a lawsuit after a loader ran out of fuel mid-operation, causing a trench collapse. Investigation revealed the fuel gauge had been faulty for months, underscoring the importance of sensor reliability.
Terminology Notes

• Float mechanism: A buoyant arm inside the tank that moves with fuel level.
  
• Sending unit: Converts float position into electrical resistance.
  
• Potentiometric sensor: A type of variable resistor used in fuel level detection.
  
• OEM: Original Equipment Manufacturer, referring to factory-authorized parts.
  

Recommendations and Final Thoughts
For Bobcat 773 owners experiencing fuel gauge issues:

• Begin with a visual inspection of wiring and connectors.
  
• Test the sending unit with a multimeter before replacing.
  
• Source parts from verified dealers using your machine’s serial number.
  
• Consider upgrading to digital sensors if operating in high-risk environments.
  

The fuel sensor may seem minor, but its failure can lead to operational delays, safety hazards, and unnecessary costs. As compact equipment continues to evolve, integrating smarter diagnostics and preventive alerts will be key to minimizing downtime and maximizing productivity.