Re: tachometer & speedometer 1997 175 Mariner
There is absolutely no relation or connection between the tach and speedometer. The speedometer has a small plastic tube running from the back of the gauge to the pitot at the back of the boat, or to the pitot built into the lower unit of the engine. Either way, the very small hole in the pitot gets plugged with debris. Clean it out and your speedo will work. If not, look for a pinched tube. As for the tach, if it works some of the time, clean and tighten the electrical connections.
