1st-Relief offers the solution against unwanted "well-back", powered by Perko Inc and ShipShapeTV

1st-Relief presents the “In-Hose” Inlet Check - Flapper Valve (ICV) to reduce or eliminate a reverse flow of fuel (well back and spit back) from the fuel tank to the fuel fill via the fill hose.
These check valves have been designed for use with plastic or metal tanks. The Inlet Check valve is designed to reduce or eliminate a reverse flow of fuel (well back and spit back).