I installed a recall switch on the tach. It works fine, for a little blip of the throttle or some lower sustained RPM's. When I make a full throttle run and check the recall, It is not accurate at all. Whats up with that?

Is it giving you a good reading in real time, and then the recall doesn't match what you saw?

Thats correct Liberator

Try bringing the RPMs up in neutral to a point where you've seen the problem, then recall that and see if the reading is good. Where I'm going with this is, I don't know your exact setup or which tach you're using. But, if you have an external switch to clear the memory, and it's an inexpensive one, it is possible that the bouncing or pounding of the boat is causing intermittent/erratic contact of the reset switch during your run which could cause weird readings. Also, make sure all your connections are solid. With a problem like that, I would usually put the tach on the bench, and test it with a distributor and coil, and a drill to spin the distributor. I don't know if you have that option. I wonder if noise in the 12v line to the tach would cause something like that? Other possibility would be faulty electronics. (Just thinking out loud)
Also, go to the manufacturer's web site. Some have troubleshooting sections which might help.

Paul

Paul, You might be onto something. It is an inexpensive switch (from Summit Racing), that I'm sure is not designed for marine use. I could'nt find one for Marine use. It is very possible that it is losing the setting because of the pounding it is expieriencing on a top speed run. Thank you, Jeff

Give it a shot, and let me know what happens. I'm curious!