Since my repower I've been running without the antisiphon valve. Don't want any resistance to flow using the cool fuel pump.

For safety I need either that or electric fuel shut off, so leaning that way. Could wire direct or use a relay.

Anyone using them?

Ayuh,...... It's a pretty simple process usin' an oil pressure switch, like Merc does it,.....

I wouldn't use an oil pressure switch, would have it turn on/off by the key.

keys get left on.........tiara yachts any many bigger others use electric valves

Sea Rays use electric fuel valves instead of anti siphon, also.

I have no experience with these.

Agree keys get left on, but if its left on then its the same as I have now with no antisiphon valve

The how to is simple, just wonder if others have done it

If your still using EFI then wire it to that pump with a rely.

That's a good spot