Eng Tach rpm drifts at 4000-5300,

[22trophy]

My 1999 force 120HP's rpm drifts,this occurs at constant throttle and engine sound. This leads me to believe it's an indicator problem. I believe there is no direct cable from engine to dash board. So I may have a problem with a voltage regulator, or my charging system. Does anyone know how I would proceed from this pt? Thanx.

 

[eurolarva]

Re: Eng Tach rpm drifts at 4000-5300,

I am not a force guy especially with electronic stuff. Can you post your model number and serial number? The year you mentioned there are two styles of ignition systems. One has a regulator/rectifier and the other one has just a rectifier. Also is this tach new or original. Have you tried testing this with all other equipment disconnected from the battery? Depth finders and Trolling motors are noise generators and can cause interference with electrical equipment. Also what type of spark plug are you using?