1988 Four Winns 200 Horizon 4.3 OMC Tachometer issue

[lasko1]

I have a 1988 Four Winns 200 Horizon with 4.3 OMC and original dash gauges. My tachometer recently started to drift to the 5800 rpm range when running higher than cruising speed (3500 rpm, 30mph). The engine sounds normal and NOWHERE near that high of rpm and my GPS speed at 7/8 throttle is about 38mph. I've read that the tach's can get moisture in them and corrode contacts or I may even have a bad ground somewhere. I truly do not believe the high tach reading because when I throttle down slightly, the tach drops quickly right back to a normal reading. Oil pressure and engine temp remain constant.

Looking at the back of my tach, I see a slotted switch which could be turned with a flat blade screwdriver. The switch has 4 positions labeled 1, 2, 3, 4. Mine is set to the #3 setting. I've read that some tach's have 4,6,8 which refers to # of engine cylinders.

Anyone know what the 1,2,3,4 on the back of my tachometer refer to or have any suggestions to resolve the tach issue? Sorry, no pictures or brand name of tach at this time.

Things I will try later today:

• Remove, clean, and reinstall all connections on back of tachometer
• Rotate the 1,2,3,4 switch through all positions and put back to original #3 setting (possibly remove any corrosion in there)
• Clean contacts coming from engine (I believe the tach wire is attached to the (-) side of my coil....correct me if I'm wrong here!!
• Remove and clean wire connections and fuses on fuse bar

Dave

 

[Scott Danforth]

most likely the internal contacts of the switch are getting whonkey. use some electric contact cleaner and rotate the switch back and forth a bit. if that doesnt resolve it, you may need a new tach

 

[Chris55]

Factory Four winns gauges are problems, there old and inaccurate, I have 3 temp gauges for my '88 and they all read high, using a laser temp gauge reads under 160, gauges are made by medallion in 1988, my tach has been replaced

 

[Lou C]

I have the same ones, they are still working but they are now 30 years old and have been in a salt water environment for at least 15 of those years, probably next winter I will replace them all.

 

[Redrig]

I had the same thing going on with a few of my orignal gauges on my 77 boat , I bought a Faria gauge kit and replaced them all . Looks much better and I have much more faith in those .