115 inline 6 tach problem

Joined
Jan 21, 2006
Messages
15
I have a '87 115 inline 6 and noticed right after I had bought it that the old tach on the boat would show anywhere from 2000 to 3000 rpm when I would start the motor and then I could tap on the tach and it seemed to start reading fine. It would also do this at wot and I could tap it and it would change the reading. I purchase a new teleflex tach and put it on my boat and ran it for a short time and started noticing that is was acting wierd. I can be runnig at wot and it will bounce up to 6200 rpm and then back down to 5000 then to 5500. It will even change if I tap the tach. I also notice that at idle that it reads 1100 rpm and based on the sound of the motor I don't think it is idling that fast. Now I don't really know what rpm I am truly running because the first tach was screwed up when I bought the boat and this new one started acting up soon after I installed it. I am going to be installing a rectifier/regulator combo in place of my rectifier that I ordered from clams. This may solve my problem and it may not. My rectifier that I currently have is not bad to my knowledge. I am only changing to a rectifier/regulator combo to solve the high dc voltage problem that these motors comenly have. Something else that may shed a little more light on this is that the boat was set up to zero out the tach when the master switch was turned on on the dash of the boat. This was a concern of mine because whenever I use my boat that master switch is on all the time and I wonder if this might be what is causing the tachs to go bad. Today I rewired the tach to only power up and zero out when I turn on the key like it supose to. I then took my boat to the lake to try it and the tach is still acting crazy. Does anyone have any advice for me?
 

Clams Canino

Commander
Joined
Jan 10, 2004
Messages
2,179
Re: 115 inline 6 tach problem

And get a new tach after you install the regulator. That one sounds like it's done.<br /><br />-W
 
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