Dropping fuel out of Fliters

[Tugcaptcp]

I have Twin F225's the Triton 2895 has just had a new Fuel tank installed & new gas hoses, at low RPM's both motors are dropping their fuel out of the Fuel / Water separators, Alarms are sounding & after pumping the primer balls tight, I must hurry up and get both motors going minimum of 1300 rpm's or they do it again, at times Starboard motor will not start..... Maybe flooded, this is getting old quick .
Anyone experienced similar issues ?
They anti siphon valves on the new tank have little valve handles on them , wondering are these to turn check valves on or off, or will closing these close the valve off completely ?

[rodbolt17]

closing the valves will shut off the fuel.
however that's not your issue.
the alarm you get is the duel engine switch alerting you to an engine stall.

your issue most likly is an air leak between the lift pump intake and the liquid in the tank or the lift pump relief valve is leaking.

the filter cup on the engine typically runs about 1/2 full.

below about 1200 RPM the lift pump runs in cycles, 20 seconds OFF then 10 seconds ON.
which is why if you keep it above 1300 RPM it keeps its prime.