Yamaha Outboard Tachometer Problem

[Alan Reagan]

All right boat mechanics. I need your opinion. The tach on my Yamaha Four Stroke is reading about 1500 rpms high all of a sudden. It started out being intermittent but now is steady.



The prop isn't slipping. It reads that high at idle also.



Is it the tach itself or should I look elsewhere?

 

[Bertram65]

I would check all the wiring first and then try a new tach, if the engine is still running fine it is probably not the engine.

 

[TJany]

i would start with the wiring... find the where the wire hooks up to the motor for the tach drive (gonna be difficult i know because its in the harness) and than run a jumper from the motor to the tach, i've seen the wiring be the problem on more than one occasion. another possible peoblem is in the plugs (i'm assuming its like a johnson with plug and play harnesses) some of the plugs can get corrosion in them and cause weird things to happen. Good luck



Tim

 

[Alan Reagan]

I had started checking the wiring Saturday but didn't get to finish. Whether I change the tach or not, I was planning on checking the plugs and using the connector grease after cleaning them.



Thanks for the responses. Hopefully, worst case is a new tach. The engine runs fine and always has. This is the first glitch with the boat in five years.

 

[TJany]

i've had tachs go weird on two different Johnson's, they both ended up being corrosion in the wires, i wouldn't be concerned about replacing the tach until you get through the wiring



Tim

 

[GAmes]

When the tach on my Johnson engine started to act up I ignored it until the voltage regulator caught on fire. :{

I also had to replace the stator under the flywheel. Don't know which failed first, the stator or the VR, but the tach gave me fair warning.