Dead Tach, need help!

[Uncivil]

Hi folks, I have a 89 70 Hp VRO that has given me some problems. Initially when i bought it the tach worked but I had problems with the engine cutting out. Has it in to check the harging system etc.etc. Turned out that the VRO pump was hooped so it was pulled. Engine runs fine alhough it seems a bit sluggish. Any way the problem is my Tach has not worked since. I have been trying to trace the wiring but it is tough because the wiring is hidden. I can't figure out where the tach wire should be connected to test. The manual is pretty weak on that sort of thing. So can anyone tell me where I should look and what colour "stock"wire i should be looking for?

 

[tashasdaddy]

Re: Dead Tach, need help!

is the motor charging the battery, rectifier is usually the problem. contaminated carbs usually suggishness, or link n sinc. have you check spark and compression??

 

[Uncivil]

Re: Dead Tach, need help!

The motor is charging and I have good spark. The carbs were supposed to have been cleaned when we took it in last year and it has been run a fair bit. We have not changed the leg oil since we bought it ( it sat for a few years) and my partner apparently hit something in the Fraser hard enough to put about a 5/16 inch dent in the prop. All these probably don't help. However before I can determine if the other problems are cumulative I need to get the Tach working. I appreciate any advice on figuring out where the Tach is connected to this motor. Thanks.

 

[emdsapmgr]

Re: Dead Tach, need help!

These later OMC's have a short pigtail harness exiting from the control box with a rubber plug on the end. The gray wire is the tach signal, black is ground and red is power.

 

[ccnstlr]

Re: Dead Tach, need help!

If your motor is charging the battery and all else checks out, your tach may actually be faulty. Check the connections there also, ground, +12v, sig, etc.

For Reference (Boating Industry of America):
Here are the standard wire colors used in the boating industry since the late 70s. When re-powering a boat with a newer motor this is a handy reference. Most boats use these standards but always double check in case changes have been made!
-------------------------------------------------
BIA Wire Color--------------------Where it is used
Black---------------------------------All Grounds
Black with Yellow stripe---------Magneto/short to Kill
Gray----------------------------------Tachometer signal
Yellow with Black stripe---------Choke
Red----------------------------------Unprotected(12V+)from battery
Red with Purple stripe-----------Protected(+12V)from battery
Purple-----------------------------(+12V)from ignition switch
Tan------------------------------Overheat sensor to warning horn
Pink-------------------------------Sending unit to fuel guage
Yellow with Red stripe----Ignition switch to starter solenoid
Yellow-----------------------------charging stator to rectifier
Lt.Blue with White stripe--------Trim up
Green with White stripe-----------Trim down