The fuel filler neck, connecting the external fuel inlet to the main tank, is a critical component with multiple functional roles in ensuring safe, efficient fueling and system integrity.
Spillage Prevention
First, its design prevents fuel spillage during refueling:
- The neck's length and curved path slow fuel flow, reducing splashing
- Many include a restrictor that creates backpressure for automatic pump shutoff
- Prevents overfilling and minimizes evaporation losses
Contaminant Protection
Second, it acts as a barrier against contaminants:
- Incorporates a fuel cap with tight seal to block dirt and water
- Some feature built-in screens or filters at the inlet
- Protects fuel system components from particle damage
Safety Note: The neck's material—often corrosion-resistant steel or high-density plastic—is chosen to withstand fuel chemistry and environmental stress. Its placement reduces fire risks by being away from hot components.
Safety Features
- One-way or rollover valves seal the tank during accidents
- Corrosion-resistant materials for long-term durability
- Strategic placement away from heat sources
Ergonomic Design
Ergonomics also influence filler neck configuration:
- Optimized angle and position for easy nozzle insertion
- Size variations to prevent misfueling (diesel in petrol tanks)
- Some feature larger openings for faster refueling