On S&B and OEM diesel fuel tanks, there are one or more rollover valves. The rollover valve uses a float/weight to close the valve when the float is immersed in fuel. This prevents fuel leakage in the event of a rollover. Gravity feed tanks or electronically controlled feed tanks can overfill the S&B or OEM tank. If/when the tank is overfilled, the rollover valves will prematurely close. Without the required vapor space in the tank, this violates the “overfill restriction” requirement of 49 CFR 393.76(12)(i). An overfilled tank can lead to a pressurized fuel tank, leaking, and tank failure.
Therefore, the use of a gravity feed tank or electronically controlled transfer tanks (that allow the S&B tank to overfill) in conjunction with a S&B Tank is dangerous and will void the S&B Tank warranty.