1999 Yamaha 90hp 2 stroke electrical issue. Tach works intermittantly

stejondeb

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Aug 26, 2010
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Good morning from Central Florida. My 1999 Yamaha, 90hp 2 stroke, it is a "C" model without oil tank, has a problem where the tach will drop to zero while the engine is running, it happens at all throttle speeds. If I fiddle with the ignition switch the tach will work for a couple seconds then quit. Also, when the tach quits, if I activate the trim/tilt switch the tach will also start working for a few seconds. All other gauges, Fuel, ammeter, continue working. This problem started out a while ago as very very intermittant and has progressed to being constant. I don't mind spending the money for a new ignition switch if that would solve the problem.
Any advise or comments are appreciated.
 

robert graham

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Re: 1999 Yamaha 90hp 2 stroke electrical issue. Tach works intermittantly

Same motor and year as mine....sounds like a loose or corroded connection either on the back of tachometer or in-line fuse/wiring. With tachometer working try jiggling the wires on the back, then if that makes the needle fluctuate, remove tachometer to clean and tighten the connections....a touch of grease on connections may help keep moisture out. The vibration and humid marine environment plays havoc with electrical connections....good luck!
 

stejondeb

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Re: 1999 Yamaha 90hp 2 stroke electrical issue. Tach works intermittantly

Thanks for the suggestion. I was just out running the boat. The tach would be failing and if I hit the ignition switch with my fist it would start working. Same result for touching the trim tilt switch. Had it apart all wires are clean and tight.
 

99yam40

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Re: 1999 Yamaha 90hp 2 stroke electrical issue. Tach works intermittantly

If all gauges are fed power from the key switch when in on position, and only tach is a problem, I would not think the switch is the problem.
You need to start looking at how everything is connected and test things

Monitoring the key on power to the tach while problem shows up should tell you if the 12 volt + is going away
 
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stejondeb

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Aug 26, 2010
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Re: 1999 Yamaha 90hp 2 stroke electrical issue. Tach works intermittantly

Thank you for all your help. I pulled tach out and tightened all connections and problem seems to be resolved. Is there a way to close thread?
 

99yam40

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Re: 1999 Yamaha 90hp 2 stroke electrical issue. Tach works intermittantly

it will die when no one posts on it
 

robert graham

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Re: 1999 Yamaha 90hp 2 stroke electrical issue. Tach works intermittantly

Thank you for all your help. I pulled tach out and tightened all connections and problem seems to be resolved. Is there a way to close thread?

That's good!....the connections on the back of tachometers seem to be Very sensitive to corrosion/tightness....may also check/clean/grease any in-line fuses....they can get corroded/loose also....
 
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