Tach question

CapeMayMike

Cadet
Joined
Jun 19, 2005
Messages
24
Rewired my boat and installed new gauges. On the ignition I followed Bombardiers diagram on the back of the package.<br /><br />Gauges, I followed the instructions.<br /><br />Engine is a 1985 90 HP Evinrude.<br /><br />When I start it the tach runs up to 600 RPM. When I rev her the tach runs down to zero rather than running upward. Almost like it's running backwards.<br /><br />Gray wire to sender terminal. Power from "A" terminal on ignition. Set at 6P.<br /><br />Any ideas? Thanks!
 

Seasport

Chief Petty Officer
Joined
May 2, 2005
Messages
410
Re: Tach question

Just a thought - are you sure the tach is compatible with that motor? I had a case once when I matched an OMC tach to a Force motor and the rectifier/regulator didn't have enough oomph to drive the tach properly. Maybe it's a faulty tach? You could get it checked out. If you could get hold of an oscilloscope you could check out the signal going to the tach to make sure that you are getting a good signal.
 

Ranger01

Petty Officer 2nd Class
Joined
May 31, 2005
Messages
106
Re: Tach question

This sounds like an electrical question. You might want to move your post there, they would have a better answer i imagine. <br />Meanwhile, seasport called it, make sure that the gauge you have is compatible with your engine. a good marina would be able to tell you.
 

Seasport

Chief Petty Officer
Joined
May 2, 2005
Messages
410
Re: Tach question

Just as a matter of interest, I fixed my problem by making up a small transistor buffer. Cost a few cents - better than buying a new tach.
 

CapeMayMike

Cadet
Joined
Jun 19, 2005
Messages
24
Re: Tach question

Seasport. Are you talking about a resistor between the sender terminal and ground? If so I've read about that I may try it. Worked for you, you say?....Did you have a similar problem?
 
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