Tachometer reading too high

J

jdupree

Petty Officer 2nd Class
Joined
Aug 11, 2006
Messages
185
I have a 1992 200 hp Mercury. When I bought the boat the tach was not working. Looks like it was a disconnected wire on the motor. I have hooked it back up but it appears to be taching about 1000rpm's more than it should and when you go to WOT it goes off the scale. It is a teleflex international tach. I noticed that there is a little switch for different settings. Could you please tell me which setting it is supposed to be on. Thanks.
 
Silvertip

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,762
Re: Tachometer reading too high

Should be set to "6P" (six pulse).
 
J

jdupree

Petty Officer 2nd Class
Joined
Aug 11, 2006
Messages
185
Re: Tachometer reading too high

Thank you sir. I want to say it was on that number. Will check it out.
 
J

jdupree

Petty Officer 2nd Class
Joined
Aug 11, 2006
Messages
185
Re: Tachometer reading too high

Looked at the back of the tach last night. It has settings for cylinders and pulses. It was set on 6c but I could not find a 6p. Would it hurt if I just cranked the motor and while it is running change the setting to see which one could be the right one? The motor should idle around 800 to 1000 rpm's. The charging system appears to be working well according to the gauge and the strength of the batteries. I didn't know if the rectifier could be acting up. Thanks
 
C

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,158
Re: Tachometer reading too high

6P is a standard setting on a tach. If yours doesn't have it, you can try the other settings. I do not think it will damage anything if you change it while the motor is running.
 
T

Tom P

Petty Officer 2nd Class
Joined
Oct 1, 2006
Messages
140
Re: Tachometer reading too high

The Telflex directions actually state that it’s no big deal to switch settings while the motor is running with the tech hooked up, Personally, I’d shut it off while switching it. It would really stick if I accidentally hit two contacts while switch it. It only takes a second to restart the motor.

Tom
 
J

jdupree

Petty Officer 2nd Class
Joined
Aug 11, 2006
Messages
185
Re: Tachometer reading too high

Thanks to all for the help. It is 6p as said but mine was wore off the back. It works great now. Thanks again!
 
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