tach lost it's smoke

[ButtonRock]

1990 70 hp johnson in a 1990 starcraft center con. While underway my tach went up in smoke. Before this it was reading about half of actual rpm. I can replace it but would like to know what would cause it before I do. Engine runs fine and seemed to be charging. 1st time poster. Thanks in advance

 

[freddyray21]

Re: tach lost it's smoke

a spike in the charge system?

 

[The_Kid]

Re: tach lost it's smoke

Since everything else is still working correctly it's probably just one of the electronic components in the tach that gave out. I had the same thing happen on my 1990 Evinrude 88. Strange thing is the next time I started the motor the tach was working again, and still is. It's just a little hard to read with the smoke residue on the inside of the glass.

 

[ezeke]

Re: tach lost it's smoke

When you turn the ignition key to the run or start position, does the gauge dial snap to zero? If so, your sender Gray wire may be compromised, or your rectifier may be the problem.

Try following Mr. Joe Reeves' instructions for checking the rectifiers that are found in the Engine FAQ forum here at iboats: http://forums.iboats.com/showthread.php?t=190636