2005 yamaha 225 4stroke connection to analog tach

Need help connecting analog tach to 05 yamaha 225 4stroke. My sea pro boat is equipped with analog tach made by Teleflex, it was connected to a mercury 200hp 2stroke EFI engine which blew up. I purchased a used 05 225hp yamaha 4stroke engine to replace it. I'm having trouble trying to figure out how to connect the tach to the engine harness. I've watched videos that talked about an engine having 4poles, 6poles etc. and have tried the different settings on the back of the tach. Also I have read something about a digitally controlled outboard needing an analog gage interface, is this the case in this situation? I hope not, as the prices on those units are a bit steep. If you have the time and the knowledge to help me out it will be greatly appreciated. Thanks!

A 2005 F225 will not be a digitally controlled motor. It will be mechanically controlled.

There is a green wire in the ten pin harness to the control box/key switch. That is the tachometer signal.

Tachometer is powered by a yellow wire, grounded by a black wire with the green wire providing the tachometer signal. Usually via a fused jumper harness from the key switch to the control box.

boscoe said:

A 2005 F225 will not be a digitally controlled motor. It will be mechanically controlled.

There is a green wire in the ten pin harness to the control box/key switch. That is the tachometer signal.

Tachometer is powered by a yellow wire, grounded by a black wire with the green wire providing the tachometer signal. Usually via a fused jumper harness from the key switch to the control box.

Click to expand...

Thanks boscoe, I'll check out the wire colors tomorrow and try to connect it again. Do you know how many poles the alternator would have? Doe's it have anything to do with the number of cylinders? The tach was working with the motor that blew up, so I hope it's just a matter of getting the correct wires connected to it.

For an F225 the tachometer is set to the 12 pole position.

Has nothing to do with the number of cylinders. Some inline 4 cylinder models use a tachometer set to the 12 pole position.

In days of old the tachometer setting was based on the number of magnets used in the flywheel. In the case of the F225 the engine control unit sends the tachometer signal to the tachometer. The ECU does what it needs to do to send the correct tachometer signal.

Not sure which setting is appropiate. any ideas?

Is there a way to check Tach signal coming from green wire? I'm getting 12.7v from the yellow wire when switching on the ignition. Also, is there a fuse located anywhere on the engine for the tach signal wire. I'm just grasping at straws now!, trying to figure something out. Thanks for your input boscoe, i'm sure it's probably easy for someone that installs these everyday, but I have no paperwork on the tach, therefore nothing to guide me.