GT 40 not running at full power

finnz wrote: yep

Make sure the servo motor is taking up all of the slack in the throttle linkage.

It is supposed to do this as part of the initialization when the key is turned to on.

Your recent battery replacement makes me suspect something is amiss electrically. Your PP needs a full 12 volts to initialize properly.

Any slack left in the throttle linkage will give symptoms similar to what you describe. Essentially the throttle will not be opening all the way.

yep

thanks joe

I have a 1998 nautique with the GT40 it has been running great all summer long. I replaced the battery a couple of weeks ago and it has not run at full power since i.e., it does not seem to plane off as fast as it should and i am only running at about 38 mph at full throttle with just me in the boat (i verified via gps to eliminate a potential speedo issue). Normally at full throttle it is running 45-47mph and takes very little time to get there. I just figured that it was the fuel filter so i replaced it as-well, but still the same issues. Also, only running at a max of 3800 rpms or so. Any thoughts or ideas?