2003 Yamaha F40 Tachometer not reading

C

CDory23

New member
Hi all,

My tachometer recently started working intermittently until it finally has just given up. Everything on the Tach is functioning except for the RPM gauge. I have twins so I eliminated the Tachometer itself being the problem by plugging in the green wire (tach wire from flywheel) from the other engine to the tach in question and it read fine. I then followed every inch of the wire looking for loose connections and the integrity of the wire itself. Everything checked out.

I am not sure where to go from here. Is there a sensor or something? The problem has to be on the engine/flywheel itself. Thanks for any help!
 
CDory23":14z10dwv said:
Hi all,

My tachometer recently started working intermittently until it finally has just given up. Everything on the Tach is functioning except for the RPM gauge. I have twins so I eliminated the Tachometer itself being the problem by plugging in the green wire (tach wire from flywheel) from the other engine to the tach in question and it read fine. I then followed every inch of the wire looking for loose connections and the integrity of the wire itself. Everything checked out.

I am not sure where to go from here. Is there a sensor or something? The problem has to be on the engine/flywheel itself. Thanks for any help!
Click to expand...

Get out the shop manual, might pick up a signal from charging coil or separate coil under flywheel. Lots of times the permanent magnet in the flywheel is rusted & generates a weak signal. :thup
 
Yuor Yami's and mine are close and I have twins too but, very unfortunately, I am not a mechanic. Wish I could help though. Best to you.

Harvey
SleepyC :moon
 
Update. The problem found was a bad rectifier. This is actually the second time this has happened on this motor. The original rectifier went out at about 750hrs, and I bought a used rectifier. I have about 1,050hrs currently and this time I will most likely buy new. I've always been a main motor/kicker guy but the twins are growing on me for do it yourself maintenance reasons. Its easy to swap out parts between the two motors to troubleshoot issues, instead of potentially buying the part you think may be the problem and having to deal with the hassle of returns. Also, when taking something apart its nice to have a mirror image right next to it. I hope there isn't a deeper issue that keeps making the rectifier fail, but if it happens a 3rd time I will go down that road. Hope this helps anybody that may have this same issue.
 
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