88 3.0 OMC Tach Trouble

[dlgarr]

Bought and 88 4Winns, that had run for two years, or so I'm told. Did a little work and got it running now, however the Tach is not reading right. At first it didn't read at all, but suddenly started reading, but nor right at all, Sometimes says it's idling anywhere from 2000-4000, then as I accelerate it might drop, or give some other random reading.
I have tried cleaning the connections on the gauge, and the connections at the alternator (no idea if it is running off the alt or not, just took a shot).

Any suggestions on next step to trouble shoot.

 

[Bondo]

Ayuh,.... Welcome Aboard,..... The tach feeds off the (-) terminal of the coil,....

Odds are ya need a new tach,.....

 

[Silvertip]

If there is a calibration dial on the back rotate it back and forth to burnish the internal contacts. Then see if it reads correctly.

 

[dlgarr]

Thanks Silvertip, I will try that.
When checking this, I found that the grey wires had been attached to the + side of the distributor. These wires also seem to be used by the ESA which is also not working. I tried moving them beck to the - terminal, no changes in either the tach or the ESA. Think the previous own could have blown something having the gray wires on the wrong side?

 

[Gilded_Splinters]

If there is a calibration dial on the back rotate it back and forth to burnish the internal contacts. Then see if it reads correctly.

Also, there's a selector for the number of cylinders. Make sure that's in the right position.

 

[Bondo]

I found that the grey wires had been attached to the + side of the distributor. These wires also seem to be used by the ESA which is also not working. I tried moving them beck to the - terminal, no changes in either the tach or the ESA.

Ayuh,..... 2 ends of the same wire,.....

The (-) wire on the coil goes to the (+)distributor, which tells the coil when to fire,.....