Why Does the Lull 1044C-54 Telehandler Shut Off After 30 Seconds

[MikePhua]

A Telehandler Built for Heavy Loads
The Lull 1044C-54 telehandler was designed for demanding construction and industrial applications, offering a lift capacity of 10,000 lbs and a reach of 54 feet. Powered by a John Deere 4045TF275 diesel engine, this machine combines rugged mechanical design with hydraulic precision. Lull, originally a standalone brand, was later absorbed into JLG Industries, which continued to support parts and service for legacy models. The 1044C-54 remains popular among contractors for its load stability and boom control, especially in masonry and framing work.
Terminology Clarification

• Telehandler: A telescopic handler used to lift and place materials at height, often equipped with forks or buckets.
  
• Fuel Shut-Off Solenoid: An electrically actuated valve that controls fuel flow to the injection pump, shutting off the engine when de-energized.
  
• Governor Flex Ring: A rubber ring inside Stanadyne injection pumps that deteriorates over time, causing fuel starvation or erratic engine behavior.
  
• Stanadyne DE10 Pump: A rotary diesel injection pump used in many John Deere engines, known for its compact design and internal governor system.
  

The Mysterious Shutdown
In one case, a Lull 1044C-54 started without hesitation but consistently shut off after 30–40 seconds of operation. The shutdown mimicked the behavior of someone turning the key off—no sputtering, no warning, just a clean stop. Attempts to restart immediately failed, but after waiting a minute, the engine would fire up again and repeat the cycle.
This pattern pointed to a fuel delivery issue, specifically involving the fuel shut-off solenoid or the governor flex ring inside the Stanadyne DE10 pump. If the flex ring begins to disintegrate, it can clog the return fitting with rubber debris—often described as “mouse turds”—causing internal pressure buildup and fuel starvation.
Diagnostic Steps and Field Solutions

• Check the return fitting on top of the injection pump. Remove and inspect for debris. Clean thoroughly and reinstall.
  
• Test the fuel shut-off solenoid by applying 12V directly to the terminal. Listen for a click and verify that it remains energized during operation.
  
• Inspect the oil pressure switch, which may be wired to disable the solenoid if pressure drops. A stuck switch can falsely trigger shutdown.
  
• Observe fuel flow at the injectors during cranking. If fuel is absent after shutdown, the solenoid or pump is likely at fault.
  

In this case, the root cause was a stuck oil pressure switch, which falsely signaled low pressure and cut power to the fuel solenoid. Replacing the switch restored normal operation.
Preventive Maintenance and Long-Term Advice

• Replace the governor flex ring every 2,000 hours or 10 years, whichever comes first.
  
• Use fuel additives that condition seals and prevent varnish buildup.
  
• Keep electrical connections clean and protected with dielectric grease.
  
• Monitor oil pressure with a mechanical gauge to verify switch accuracy.
  
• Maintain a service log for all pump and solenoid work.
  

Conclusion
The Lull 1044C-54 telehandler’s sudden shutdown after 30 seconds was traced to a faulty oil pressure switch affecting the fuel shut-off solenoid. While the Stanadyne DE10 pump is robust, its internal flex ring is a known wear item that can cause similar symptoms. With careful diagnostics and preventive maintenance, operators can avoid costly downtime and keep this reliable machine performing at its best.