1987 Johnson 60hp 3 cyl Tachometer Burned

[Ficht Guy]

Hi,

I installed a factory omc tachometer on my 1987 Johnson 60hp 3cyl outboard last year. I used the factory harness and plugged into the throttle control box. It worked great all last year and then all of the sudden it started burning this weekend. The needle melted and the glass screen turned black. The top of the tach is where it looks like it burned. Any idea what would have caused this? The engine also seems to miss at shutter at certain rpms. What can I check to make sure this doesn't happen again? Thanks for your help. Model# of engine is J60TLCUC

 

[Rustywrench]

Do you have other electrical gear on the boat? A volt meter by chance? Would like to know if you are expert in high battery voltage. CDI makes a rectifier with some regulator ability. #193-3408. This motor only has a rectifier & depend on you using the excess voltage using the trim often enough to bleed off excess. If you don't have other items using voltage (radios, depth finders, etc.) then you can experience high voltage in just the right application.

 

[Ficht Guy]

I do have a depth finder, trim gauge, and fuel gauge. I have seen tachometer harnesses with a fuse block but with mine I just plugged it into the throttle control box with the oem wire harness.

 

[Ficht Guy]

If I replace the rectifier does the flywheel need to be pulled on that engine?

 

[Silvertip]

In order for the tach itself to burn, the problem was at or inside the tach. If the tach had threaded posts with nuts that secured the power, ground, light, and sense wires to the tach, you may have actually twisted the stud(s) which created and internal short inside the gauge. If the other gauges are working, then damage has been limited to that gauge.

 

[flyingscott]

Agree with silvertip look at the tach. I have run my tachs with the same set up and had no problems.

 

[Fed]

You might want to check the size of the fuse under the cowl to make sure someone didn't put a big one in there.
Although a bigger fuse won't have caused your tacho fault it may have allowed it to cook instead of blowing the fuse.
FWIW OMC tachos can run happily on an unregulated Voltage of 18V.

 

[jakedaawg]

Check the light bulb in the tach