Troubleshooting Boom and Hydraulic Issues on the Faresin Houlotte FH 3500/14F

[MikePhua]

The FH 3500/14F and Its Hybrid Lineage
The Faresin Houlotte FH 3500/14F is a rare telehandler model born from a collaboration between two European manufacturers—Faresin Industries of Italy and Houlotte Group of France. Faresin, known for its agricultural mixers and handlers, and Houlotte, a global leader in aerial work platforms, briefly partnered to produce hybrid machines that combined lifting reach with compact maneuverability. The FH 3500/14F was designed to offer a 3.5-ton lift capacity and a 14-meter boom reach, making it suitable for framing, roofing, and light industrial tasks.
Due to its limited production and niche market, documentation and parts support for the FH 3500/14F can be difficult to source, especially in North America. Owners often rely on reverse engineering and hydraulic diagnostics to maintain functionality.
Symptoms of Boom Malfunction and System Lag
A common issue reported with this model involves the boom failing to extend or respond, despite other functions—such as outriggers and oscillation—working intermittently. In one case, the oscillation system operated but at a noticeably slower rate, suggesting a broader hydraulic flow issue.
Key symptoms include:

• Boom remains stationary despite joystick input
  
• Outriggers functioned previously but now show reduced speed
  
• Oscillation system operates slowly
  
• Joystick replacement did not resolve the issue
  
• No audible pump surging or cavitation
  

These symptoms point to a possible restriction in hydraulic flow or a malfunctioning safety interlock preventing full system engagement.
Terminology Clarification

• Joystick Control: An electronic or hydraulic input device that sends signals to the control valve to actuate boom and auxiliary functions.
  
• Hydraulic Suction Filter: A pre-pump filter that prevents debris from entering the hydraulic pump; clogging can starve the system.
  
• Bypass Flow: Hydraulic fluid that returns to the tank without performing work, often due to valve misalignment or safety lockouts.
  
• Pressure Gauge Test: A diagnostic method to measure hydraulic pressure at various points in the system to identify flow loss or blockage.
  

Diagnostic Strategy and Pressure Testing
To isolate the fault, technicians should begin by installing a pressure gauge between the pump outlet and the main control valve. This helps determine whether the pump is generating pressure and whether flow is being diverted or blocked.
Recommended steps:

• Inspect and clean the suction filter before testing
  
• Verify joystick signal continuity using a multimeter
  
• Check for safety interlock switches that may prevent boom activation
  
• Test pressure at the pump outlet and control valve inlet
  
• Observe flow behavior when actuating different functions
  

In one field case, a technician discovered that a safety switch near the boom base had failed, preventing the control valve from opening. Bypassing the switch temporarily restored boom movement, confirming the diagnosis.
Electrical and Hydraulic Interplay
The FH 3500/14F uses a combination of electrical switches and hydraulic logic to manage safety and function sequencing. If a switch fails or a relay misfires, the system may default to a safe mode, disabling boom movement. This is especially common in machines with aging wiring harnesses or exposed connectors.
Checklist:

• Inspect all safety switches, including seat, boom angle, and outrigger sensors
  
• Test relays and fuses for continuity and amperage draw
  
• Clean and reseal connectors with dielectric grease
  
• Verify that the joystick is sending correct voltage signals to the valve solenoids
  

A mechanic in Saskatchewan reported that a similar issue on a Manitou telehandler was caused by a corroded relay under the dashboard. Replacing the relay restored full hydraulic function.
Pump Health and Flow Behavior
If pressure tests reveal low or no pressure, the pump may be bypassing internally or suffering from worn vanes or pistons. However, a pump failure typically affects all functions evenly. In this case, the selective failure of the boom suggests a control issue rather than pump degradation.
To confirm pump health:

• Listen for pump surging or whining under load
  
• Check fluid temperature after extended operation
  
• Inspect return lines for excessive flow, indicating bypass
  
• Test pump output with a flow meter if available
  

If the pump is confirmed healthy, attention should shift to the control valve and associated solenoids.
Preventive Maintenance and Long-Term Strategy
To maintain reliability in rare machines like the FH 3500/14F:

• Replace hydraulic fluid every 500 hours or annually
  
• Clean suction and return filters quarterly
  
• Inspect wiring harnesses for abrasion and corrosion
  
• Keep a log of pressure readings and function behavior
  
• Source spare parts from European suppliers or compatible models
  

For machines operating in cold climates, use low-viscosity hydraulic fluid and warm up systems before full operation to prevent valve sticking.
Conclusion
Boom failure on the Faresin Houlotte FH 3500/14F is often rooted in hydraulic flow restriction or electrical interlock malfunction—not necessarily pump failure. By combining pressure testing, electrical diagnostics, and component inspection, operators can restore full functionality and extend the life of this unique telehandler. In rare machines, knowledge and methodical troubleshooting are the most valuable tools in the toolbox.