Troubleshooting the Thomas 173HL II Skid Steer: Stalled and Will Not Start

[MikePhua]

The Thomas 173HL II skid steer is a versatile and reliable piece of machinery used for a wide range of construction and landscaping tasks. However, like any heavy equipment, it is not immune to mechanical issues. One of the more frustrating problems operators can encounter is a situation where the skid steer stalls and refuses to start again. This issue can be caused by a variety of factors, ranging from fuel delivery problems to electrical system failures.
In this article, we will explore the possible causes of a Thomas 173HL II that stalls and won’t start, as well as the steps you can take to troubleshoot and resolve these issues.
1. Initial Considerations: Safety First
Before diving into troubleshooting the Thomas 173HL II, it’s important to take some basic safety precautions. Skid steers are powerful machines, and ensuring the environment is safe to perform maintenance or repairs is critical.

• Ensure the Machine is Off: Always make sure the skid steer is turned off and that the parking brake is engaged before attempting any repairs.
  
• Check for Leaks: Inspect the machine for any visible fuel, oil, or hydraulic fluid leaks that may cause safety hazards.
  
• Consult the Manual: Before proceeding with any repairs, consult the operator's manual for the Thomas 173HL II. The manual provides valuable insight into the specifications, troubleshooting procedures, and recommended maintenance schedules.
  

2. Common Causes of Stalling and No Start
Several factors can contribute to a skid steer stalling and not starting again. The most common causes are related to fuel supply, electrical issues, and engine components. Let’s go over each potential cause in detail.
Fuel System Issues

• Fuel Starvation: One of the first things to check when a machine stalls is the fuel system. A blocked fuel filter, clogged fuel lines, or a faulty fuel pump can all result in insufficient fuel reaching the engine, causing the machine to stall. Over time, dirt and debris can build up in the fuel system, leading to blockage and reduced fuel flow.
  
• Fuel Contamination: If water or dirt enters the fuel system, it can cause the engine to stall or run inefficiently. Contaminated fuel can be drawn into the engine, causing it to misfire or shut down. To fix this, drain the fuel tank, clean the lines, and replace any damaged components.
  
• Air in the Fuel Lines: Air in the fuel lines can prevent the engine from starting or cause it to stall. Bleeding the fuel lines may help resolve this issue, allowing fuel to flow properly to the engine.
  

Electrical System Failures

• Battery Problems: A weak or dead battery is another common cause of starting issues. If the battery isn’t providing sufficient power, the starter motor won’t engage, and the engine won’t turn over. Check the battery voltage using a multimeter. A fully charged battery should read around 12.6 volts. If the voltage is low, recharge or replace the battery.
  
• Fuses and Relays: Electrical fuses and relays are critical to the machine’s starting and operational systems. A blown fuse can interrupt power to the starter, fuel pump, or ignition system. Inspect all fuses and relays and replace any that are blown.
  
• Ignition Switch: The ignition switch itself may be faulty. If turning the key doesn’t activate the electrical system, the ignition switch might need to be replaced.
  

Engine and Starter Issues

• Starter Motor: If the engine isn’t turning over, the issue may lie with the starter motor. A malfunctioning starter may fail to engage properly when the ignition key is turned. Listen for a clicking sound when attempting to start the engine, which may indicate a faulty starter. If the starter motor is faulty, it will need to be replaced.
  
• Starter Relay and Solenoid: The starter relay and solenoid control the operation of the starter motor. If either of these components is defective, the engine won’t start. You can test these components by bypassing the relay to check if the starter motor engages.
  
• Glow Plugs (Cold Weather): In colder temperatures, the glow plugs play a crucial role in starting the engine. If one or more glow plugs are faulty, the engine may struggle to start, or fail to start altogether. If you’re experiencing cold start issues, check the glow plugs for wear or damage.
  

3. Diagnostic Steps to Take
If your Thomas 173HL II has stalled and will not start, follow these diagnostic steps to help narrow down the cause of the issue:
Step 1: Check for Fuel Issues

• Inspect Fuel Filters: Start by inspecting the fuel filters for clogs or damage. If they appear dirty or blocked, replace them with new filters.
  
• Check Fuel Lines for Blockages: Inspect the fuel lines for kinks, leaks, or signs of wear. Make sure that fuel is flowing freely to the engine.
  
• Drain the Fuel Tank: If you suspect fuel contamination, drain the fuel tank and replace the fuel with fresh, clean fuel.
  
• Bleed the Fuel System: If you have air in the fuel lines, you’ll need to bleed the system to remove the air pockets and ensure proper fuel flow.
  

Step 2: Inspect the Electrical System

• Check the Battery: Use a multimeter to check the battery voltage. If it’s below 12 volts, recharge or replace the battery.
  
• Inspect Fuses and Relays: Check the fuses and relays in the electrical system. Replace any blown fuses and faulty relays.
  
• Test the Starter Motor: If the engine is not turning over, inspect the starter motor for damage. Listen for any unusual clicking sounds when attempting to start the machine, which could indicate a faulty starter.
  

Step 3: Examine Engine Components

• Test the Ignition Switch: If the electrical system seems to be working but the engine still won’t start, check the ignition switch for defects.
  
• Check the Glow Plugs: For cold weather starting issues, check the glow plugs to ensure they are functioning properly. If necessary, replace any faulty glow plugs.
  
• Inspect the Starter Relay and Solenoid: Test the starter relay and solenoid for faults. Bypass the relay to see if the starter motor engages.
  

4. Preventive Maintenance Tips
Once you have successfully diagnosed and repaired the issue, it’s important to perform regular maintenance to prevent future problems. Here are some tips for maintaining the Thomas 173HL II skid steer:

• Regular Fuel System Maintenance: Replace fuel filters every 250-500 hours, or as recommended by the manufacturer. Keep the fuel tank clean and free from contaminants.
  
• Battery Maintenance: Keep the battery terminals clean and ensure the battery is properly charged. Check the battery regularly for signs of wear or damage.
  
• Electrical System Inspections: Regularly inspect electrical components such as fuses, relays, and wiring to ensure they are functioning correctly.
  
• Engine Care: Change the engine oil at recommended intervals, inspect the starter and glow plugs periodically, and monitor the overall health of the engine.
  

5. Conclusion
The Thomas 173HL II skid steer is a reliable machine, but like any complex piece of equipment, it may occasionally experience issues that prevent it from starting. By following a systematic diagnostic process, checking the fuel system, electrical components, and engine parts, you can identify and resolve the problem. Regular maintenance and inspections will help keep your skid steer running smoothly and minimize the chances of encountering starting issues in the future.
With these troubleshooting steps, you can ensure that your Thomas 173HL II is up and running efficiently, allowing you to get back to work in no time.