An anti-siphon valve is a one-way valve that prevents this. It can have a rubber diaphragm that prevents backups, a spring-loaded check valve, or an air relief valve.

I solved this by opening each dripper valve more and shortening the pump's runtime to account for the higher flow rate. Sancruz prevented this issue by including an anti-siphon valve in the box.

To prevent this, an automatic spring-loaded valve is in the fitting that leaves the fuel tank. The valve is closed when the engine isn’t running; open when the engine is running, allowing fuel ...