Merc 75hp tach

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Old Salt

Cadet
Joined
Jan 21, 2004
Messages
23
I have 1 1995 75hp merc on a 1995 17' starcraft fishing rig. Just before I put it to bed for the winter I noticed the dash mounted tach was not working. I checked fuses and wires for cuts etc. but there was no obvious problem. How should I troubleshoot this. <br /><br />Thanks for any help.<br /><br />Old Salt
 
WillyBWright

WillyBWright

Fleet Admiral
Joined
Dec 29, 2003
Messages
8,200
Re: Merc 75hp tach

The tach signal comes from the regulator/rectifier. If that's bad, no signal.<br /><br />Easiest way to test it is to see if the charging system is working. You should get over 13 volts at the battery with the motor running. If it stays at less, then it isn't charging (and sending a tach signal). The part most likely to fail is the regulator/rectifier. Could be a stator or a gauge, too.<br /><br />Regulator/rectifier failures are frequently caused by loose or corroded battery connections and accidentally hooking the battery cables up backwards. :eek:
 
D

dilligafda

Petty Officer 1st Class
Joined
May 13, 2003
Messages
315
Re: Merc 75hp tach

One other quick test is to connect one of the yellow stator leads to the gray tach lead and run the engine. If you have a tach, then replace the regulator/rectifier if you don't replace the stator.<br /><br />Good luck!
 
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