How to Fix a Leaking Sump on Your S&B Tank

If your S&B fuel tank has a leaking sump (typically a slow drip), the most common cause is over-tightening the fitting during installation. Excessive torque can slightly deform the plastic at the connection point, breaking the seal and allowing fuel to leak.

The good news — this issue is easily fixable. We offer three fitting replacement options below, and we’ll provide the fitting you need free of charge.

Replacement Fitting Options

  1. Sump Plug Kit – Ideal for sealing the sump if you are not using a hose connection.
  2. 1/2" Fuel Hose (1/2 NPT to -8 AN) – Commonly used for 1/2" fuel line applications.
  3. 5/8" Fuel Hose (1/2 NPT to -10 AN) – Recommended for larger 5/8" fuel line systems.

Installation Tips

  • Apply a quality thread sealer (not Teflon tape) to the new fitting.
  • Tighten the fitting until it fully bottoms out on the tank—do not follow the “25 ft-lb” torque spec printed on the tank.
  • For easier access, drive the truck until the tank is nearly empty, or tilt the vehicle slightly (such as on a curb) to move the fuel away from the sump area.
  • If removing fuel, store it in a clean container and refill once the fitting replacement is complete.

Following these steps will ensure a proper seal and prevent future leaks. If you need additional help, please contact S&B Customer Service.