Evinrude Tach

[robh693]

1986 Evinrude 88 SPL. Tach only reads when starting. As soon as it fires, the tach quits. Any quick thoughts? Thanks.

 

[tashasdaddy]

Re: Evinrude Tach

welcome to iboats. bad rectifier. is your battery charging. check voltage at battery with motor off, the start, and recheck. if it is not charging, 99% rectifier.

 

[HighTrim]

Re: Evinrude Tach

Is this a new motor to you or did it recently start doing this? Are you familiar with testing diodes with a MM? Do you have a manual?

 

[F_R]

Re: Evinrude Tach

The tach gives a reading when cranking? Sounds to me like it isn't getting a 12v supply from the key switch when you release the key from the "start" to the "run" position.

 

[robh693]

Re: Evinrude Tach

I have a Clymer manual for this motor but it doesn't provide any information on the shift box or the tach feed from it. The teleflex web page only provides an extremely basic installation diagram now. If anyone knows where schematics for the guage or shift box can be found that would help. The 3 pin plug out of the shift box has what looks like a ground, a feed and a third wire that I can't identify.

 

[F_R]

Re: Evinrude Tach

Needs a ground, a 12V supply, and a signal wire (grey). The grey wire comes from the alternator rectifier and the tach counts the AC pulses from the alternator. If the alternator isn't working, then the tach won't either, obviously because there aren't any pulses to count.

 

[ezeke]

Re: Evinrude Tach

Copy the link to your browser without the quotation marks.

The Boston Whaler site has a good reference/diagrams for your control wiring:
"http://continuouswave.com/whaler/reference/ignitionSwitch.html"

 

[wavrider]

Re: Evinrude Tach

Works while cranking?

Sounds like the +12v for the tach is connected to the cranking side of the ignition switch.

Try connecting the 12v+ for the tach to a known good power source and see what happens.

In theory if it is reading while it is turning over then the rectifier is most likely good but still need +12 for the tach to work. Good luck.