Using a fuel injector as FAV?

[rotrex]

Unless the injector is rated for high water content and methanol compatibility, I'd refer from using it. I think with injectors compatible with methanol, you might have a chance.
A common fuel injector will corrode in short oder and fail.

Alternatively you can build a test rig and test the injector daily for a few weeks with water/methanol (constant exposure) and check if it works without isses.
That is the only other way to find out.

I'd rather buy the FAV from Aquamist and call it a day. Won't be really more expensive than that injector, a holder and associanted pipe fittings.