Understanding S&B Tank Venting and Fill Behavior

S&B Tanks are designed with a precise venting system that allows air to escape as fuel enters during refueling. The ¾" red vent serves as the primary fill vent. As the fuel level rises and reaches the height of this vent, air flow is restricted. This causes fuel to back up slightly into the filler hose — which triggers the automatic nozzle shutoff and stops the fill process.

The orange vents on the tank are rollover valves, not part of the filling system. Each is equipped with a small 2mm orifice that allows for limited air exchange during normal vehicle operation, but not during refueling. Their main function is to prevent fuel leakage in the event of a rollover or extreme tilt.

Quick Tip:
When diagnosing fill rate issues, always check that the red vent line is free of kinks or obstructions. Any restriction in this vent can cause slow filling or premature nozzle shutoff during refueling.
S&B Tank Venting Overview
Diagram showing S&B tank venting layout and rollover valve placement.