I have a 16' Alumacraft boat with a 40 horse Yamaha on the back, but the console speedo does not work. I know this is not a huge deal because I have a speedo on my Humminbird, and my speed with the 40 is not something to be too worried about, but I thought if it was a easy fix I would like to try and fix it so all of the console gauges work.  The boat and motor are both '92's or 94's, I cannot remember right now, pretty sure they are 92's.

Thanks

Typically the problem is some kind of debris in the intake hole. 

Get a 1/8 or smaller drill bit.  Use your fingers not a drill or pliers.  Slowly screw it into the water intake hole about 1/4" then pull it out. 

Keep going deeper until you have the hole cleaned out and see if that is a fix.

As far as I'm concerned, Speedo's don't work for any guy!