You asked about fuel consumption in a V6 Evinrude.
My Johnson GT200 (1987) burns about 9 gals/hr at cruise. That is pushing a 20'
cuddy at about 22 knots (gps indicated) according to my flowmeter.That is
optimum mileage. At wide open it is around 20 gals./hr
I hope this helps.
My prayers are with you.
Cliff