New Holland L‑170 Skid‑Steer Loader Hard‑Start Phenomenon

[MikePhua]

Context and Overview
Owners of the New Holland L‑170 often report the machine being hard to start—a phrase that means the loader cranks over but takes excessive effort, time, or multiple key cycles to fire up. This struggle can stem from both fuel and electrical systems, each demanding its own inspection and troubleshooting path.
Underlying Causes and Mechanisms

• Electrical power delivery faults
  • Voltage drops due to corroded battery cables, poor relay connections, or worn contact surfaces in the starter solenoid. Even if the solenoid clicks, this doesn’t guarantee enough current reaches the starter motor.
    
    
  • Starter gear misalignment: Some operators have found that adding a thin thin washer spacer to the starter mounting bolts helps the starter gear mesh more reliably with the flywheel. This adjustment prevents the “click but no spin” symptom.
    
    
  • Safety interlocks—such as seat switch, seatbelt sensor, or ignition fuses—can intermittently fail, preventing startup. In one case, a broken microswitch in the seatbelt buckle caused cranking without starting, eventually fixed by sourcing a part from an old pickup truck for just $10.
    
    
• Fuel system and combustion challenges
  • Air trapped in the fuel lines or a clogged intake screen may prevent proper fuel delivery, causing extended cranking before ignition. Bleeding the lines or clearing the tank screen can help.
    
    
  • Contaminants—like water or debris in diesel—can hinder spray quality at the injector tips. Dirty or failing injectors, improper valve clearance, worn or leaking injection pumps need to be examined and serviced.
    
    
  • After sitting idle, pressure may bleed off in the pump or lift circuit. A previously stuck plunger in the injection pump, for instance, can create delayed or repeated start difficulties.
    
    

Illustrative Cases and Anecdotes

• A user recounted the loader would start smoothly right away, but after a 20‑minute rest, required prolonged cranking to fire. Even replacing the lift pump offered no relief—raising suspicion that residual air was bleeding back into the fuel system or a faulty solenoid wasn’t engaging consistently.
  
  
• Another instance featured consistent cranking and black smoke upon start attempts—the telltale signs of fuel reaching the engine—but still no ignition, leading to a deep dive into compression and injector function.
  
  
• One creative work-around involved discovering a blown 5 A fuse for the fuel solenoid. Though the fuse wasn’t fully blown, its poor contact prevented solenoid activation. A bit of makeshift fixing—wedging a small piece of conductive material—restored the fuel system and saved a lot of diagnostic pain.
  
  
• In a tale of persistence, after checking fuel pump, filters, and verifying power to the solenoid, an owner discovered that a tiny microswitch in the seatbelt buckle was intermittent—replacing it for a mere $10 salvaged the machine.
  
  

Technical Glossary & Annotations

• Starter solenoid: An electromechanical switch that controls heavy current from the battery to crank the starter motor.
  
• Voltage drop: Loss of current or voltage across a connector or length of wiring due to corrosion, resistance, or loose contact.
  
• Air bleed: Removing trapped air from fuel lines, which can disrupt continuous fuel delivery.
  
• Lift pump: A low-pressure pump that feeds fuel to the injection pump; loss of pressure can starve the system.
  
• Injection pump: A high-pressure component sending timed fuel pulses to injectors—critical for combustion.
  
• Injector nozzle: The tip that atomizes diesel into the cylinder; defects here can keep the engine from igniting fuel.
  
• Sensor interlocks: Safety switches (e.g., seat switch, seatbelt switch) that must be correctly engaged for the machine to allow starting.
  
• Fuel solenoid: A valve or switch that controls fuel flow into the pump; must be powered to allow engine starts.
  

Approach to Diagnosis: A Step‑by‑Step Perspective

• Step 1: Start with the electrical system
  • Clean and inspect battery terminals; ensure ground and starter cable continuity.
    
  • Test starter solenoid operation and smoking or gear engagement issues. Add shims if needed for proper meshing.
    
  • Check safety interlocks—seat switch, belt sensor, ignition fuses—and bypass temporarily to identify hidden faults.
    
• Step 2: Verify fuel pathway and delivery
  • Bleed fuel lines and check for air intrusion. Replace filters and clean inline screens.
    
  • Examine solenoid power under key-on and crank; ensure the valve is functioning.
    
  • Inspect injectors and pump for leaks, poor spray, or unusual pressure characteristics. Check valve clearance.
    
• Step 3: Confirm combustion capability
  • Observe exhaust while cranking—black smoke indicates fuel, white suggests cold or misfiring.
    
  • Conduct compression test if the engine spins well but won’t catch.
    
  • Rule out timing issues or burned injection pump components.
    

Closing Thought & Practical Reflection
These hard‑start moments are often rooted in small but critical faults—like a corroded contact or a stuck microswitch. Patience, systematic testing, and a bit of ingenuity (like the fuse contact fix) can go a long way. Remember, a loader is built tough—but sometimes it’s the tiny, overlooked part that hinders its roar.