95 Johnson 88spl Tach drops at high rpm

[POORBOY]

sometimes while running at wot 5200 rpm My tach indicator will start going down will stay at about 1000, retard the throttle and it will climb right back up,and even stay there.. sometimes.I notice a miss ever 5-10 minutes while trolling,nothing great but I know it's there.Its been doing this for about a year now so no real problem just a pucker factor. Have taken it to both of the marine dealers here in Abilene Tx, they can't find a thing wrong, Any ideas as to what we're missing .Had it since new runs like a stripped a--ape on the water never a lick of problem, Oh and it's charging good 12.5 to 14.5 depending on real rpm.,

 

[Whaler15SS]

Re: 95 Johnson 88spl Tach drops at high rpm

Bad voltage regulator.

 

[bonitoman]

Re: 95 Johnson 88spl Tach drops at high rpm

Two things that come to mind. If you have a plug that goes into the control box for your tach is not all the way in or your rectifier is bad.

 

[Reelistic]

Re: 95 Johnson 88spl Tach drops at high rpm

If you fail to find any loose wires, I would check to make sure your battery is charging. The tach signal comes from the voltage rectifier/regulator. Easiest way to check the rect/reg is to connect a voltmeter across the battery terminals... voltage should be in the neighborhood of 12 volts. Start the motor and increase throttle... voltage should approach 14 volts. If the voltage remains at 12 volts or less, you may have a faulty regulator. Resistance checks of the stator windings will help confim.

 

[POORBOY]

Re: 95 Johnson 88spl Tach drops at high rpm

Thanks guys, been there done that.Kind od hard to fix something that isn't broke, never ever acts up with some one else on board, Marine mechanic run it in test tank for 1 and 1/2 hour. 12.5 volts at 700 RPM 13.2 volts at 1500 RPM and 14.5 at wot or 5200RPM . Thanks again guess I'll just run it until something drops out all togather.