I just had a 2005 6.2 320 HP Merc Horizon installed in a 25' Checkmate Convincor. I had been using a 14 X 19 3 blade prop with the old 250 HP motor and with this I put a 14.5 X 21 3 blade prop. I can not get beyond 2300 RPM with it in the water. I have only 2.5 hours on the motor. I verifiied the tach is correct using an inductive pick up tach. Any ideas?

Mark

Which drive do you have?

a rebuilt Bravo 1. I put in smartcraft tach and now hitting close to 4000 rpm. seems the old tach must have been effecting the tach reading some how. Still boat performance is poor. I am going to try some different props.

At what point did or have you replaced the drive? Did you have the same drive from the time you installed the motor? Did the motor ever run to peak rpm? Is this a problem the was also with the old motor? I don't believe this would be drive ratio related, the rpm wouldn't drop near 2500. So, its onto the installation. Does your boat have a fuel shut off valve? Is it open? Next, voltage. Is the alternator putting out at least 13 volts? Are all the battery connections tight? Did you or anyone else set the timing correctly?

Just a few thing inquiring minds want to know.

John

Sounds like your in "limp home" mode for some reason. Check for codes and issues as above. Fule pressure and/or fuel seperators good place to look also. Good luck