Johnson Tach Problem

Snake334

Seaman Apprentice
Joined
Dec 30, 2010
Messages
35
I installed a new tach on my boat, and it's not working correctly. I have searched the forums, but I haven't found exactly what I'm looking for. I have a 1998 Johnson 70hp. The wiring harness had the tach wires already attached. I went to Bass Pro and bought a new tach. I installed it exactly how the directions said. I made sure the dial on the back was turned to the correct position. When the engine is off, the tach stays at around 1000 RPMs. When it's idling, it never goes below 1500. As you increase throttle, the tach will climb to about 4000, then drops back to zero. It stays there until you shut it off and start it again. I have checked the wire connections at the gauge, but I'm not sure where to check the wires at the engine. I have 3 plugs on the engine end of the harness, and not sure which one has the tach wires. I have checked the charging system, and it is working perfectly. Any help would be greatly appreciated.
 

boobie

Supreme Mariner
Joined
Nov 5, 2009
Messages
20,826
Re: Johnson Tach Problem

What # did you turn the dial on the back to ?? The gray wire coming off of the mtr feeds the tach it's signal.
 
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