Mercury 115 tach problem

[Grizcat]

Hi! I have a 95' Mercury 115 elpto and don't think I should be running 8000 rpm down the lake. Something happened to the tach over the winter that is causing it to not give me the correct reading. It is idling at 2000 rpm, the boat had been fine when I put it away last fall. I was running at 5300-5400 WOT. Doe's the tach read off the coil or how does work. I guess I'm looking for a starting point to look and would appreciate any help I could get. I noticed that sometimes at WOT it will read 6400 and then next time it will be 8000, but I can hear that the motor sounds normal. Thanks for the insight!

 

[Barnacle_Bill]

Re: Mercury 115 tach problem

Look on the back of the tach and you should see an adjustment to match the tach to the motor. Yours should be set to 6P (pulses) or 12 poles. Using a screwdriver turn it back and forth several times stopping EXACTLY on the proper setting. Close don't count. You may luck out and clear any corrosion that may have built up on the contacts in there.