[compcrasher86]

Hey guys I just had my '87 Evinrude 140hp V4 rebuilt and shes purring like a kitten. I wanna hook up a tach gauge to the engine but the only wiring present in the center console of my '85 Aquasport are the starter and hydraulic tilt wires. This engine must have sensors everywhere cause it fires off a horn in the controller assembly whenever the engine over revs or if im low on oil and on startup etc.

If somebody could tell me what to wire and where to wire it for a tach gauge that would be awesome. I can take pics tomarrow if necessary

[Silvertip]

Check right below the key on the control box. There may be a three wire tach connector there.

[compcrasher86]

Thanks silvertip! the connector was right there so I'm just going to splice into it for my new tach. i found a useful diagram of the standard OMC wiring for any others it may benefit on this page. My engine is wired exactly as this, and other evinrude/ johnsons may be as well (Scroll all the way down)

http://continuouswave.com/whaler/ref...ionSwitch.html

[bob01081969]

Should be a purple or violet color wire make sure you hook to corect wire or you will blow the 20 amp buss fuse or worst

[dajohnson53]

Originally Posted by compcrasher86

... This engine must have sensors everywhere cause it fires off a horn in the controller assembly whenever the engine over revs or if im low on oil and on startup etc....

I'm not sure about the over rev alarm. The OMC alarms are for fuel restriction, overheat, low oil and no oil (and like you said, a test beep on startup). If you're getting an alarm that you think is over rev, it must be something else, one of the above?