Excessive fuel usage

[goodrich]

I have a 1990, 90 HP Evinrude with a freshly rebuilt power head and a new power pack, it runs and idles good but my fuel economy isn't economic. 3 MPG at best. I'm running a 17 pitch prop @ around 4000 RPM. if this means anything. HELP.

[boats.net]

If 4000 rpm's is all you get at wide open then need to drop to around a 11-13 pitch prop.