My boat currently has an old AirGuide Sea Speed tach installed, and was there when I bought the boat. It has never read correctly. Will show the motor as idling around 3,000rpm, and even the slightest bit of throttle application will cause the gauge to peg high at 7,000+ rpm. It's obvious that the motor is not actually idling at those speeds. I pulled it out of the dash, and found the jumper wire to be connected between terminals 1, 3, and 4. I tried every other combination of jumpers, and one of them would show idling around 1,000rpm, but still would shoot up to 5,000+ right off idle.
This is my first 2 stroke motor, and I've never before worked on these old tachs, I really don't know if it's a problem in the wiring, tach signal, or the tach itself, so I was just going to replace it with a new gauge. That said, do I need one of the expensive "marine outboard" tachs, or can I toss in one of the automotive style Autometers that I already have sitting on the bench here? Obviously the auto style wouldn't necessarily be sealed against moisture, though I'm really just looking for something functional at the moment so I can properly tune the motor and prop for the boat.
This is my first 2 stroke motor, and I've never before worked on these old tachs, I really don't know if it's a problem in the wiring, tach signal, or the tach itself, so I was just going to replace it with a new gauge. That said, do I need one of the expensive "marine outboard" tachs, or can I toss in one of the automotive style Autometers that I already have sitting on the bench here? Obviously the auto style wouldn't necessarily be sealed against moisture, though I'm really just looking for something functional at the moment so I can properly tune the motor and prop for the boat.
