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Tach Trouble

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Franco Delarossi

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I recently noticed that the t

I recently noticed that the tachometer on my 1998 90HP Johnson Spcl. Drops to zero and back while I am running. Where should I start looking? Thanks In Advance.
 
"Franco.... That usually indic

"Franco.... That usually indicates a intermitent tachometer, a internal problem within the tach itself. However, if you engine has a water cooled voltage regulator/rectifier (sits on top of the block, right in back of the flywheel), and the internal portion of that item is failing, that could also cause that problem.

The easiest way to trouble shoot that problem is to borrow and temporary install another tach. If the problem persists, the regulator/rectifer is faulty.... If the problem does not exist with the borrowed tach, replace the tach.

Joe
"
 
I have a 1996 Johnson V4 Outb

I have a 1996 Johnson V4 Outboard 115hp. The warning buzzer on the engine will come on at low RPM. Plenty of water is coming out of the pee hole when the buzzer comes on. If you increase the RPM and run the boat harder the buzzer stops. One side of the engine (two cylinders) is cool the other side (two cylinders) is warm to hot when the buzzer comes on. The boat had been sitting for several months before this started happening. Where should I start?
 
" Bruce: Johnson made 2 differ

" Bruce: Johnson made 2 different 115HP outboards: a 90-degree Crossflow block (Older design) and a 60-degree Looper block. If you have the newer engine, the thermostats have very small holes that love to clog-up. Remove them and clean them up or replace them. If you have the older block, the thermostats love to stick shut after sitting for a few months. Back the boat down a ramp while still sitting on a trailer and rev-up a few times to open the thermostats up. "
 
" Franco: If the tachometer is

" Franco: If the tachometer isn't the problem, it could be the rectifier. Most V-4 "Special" motors have an unregulated charging system. If the tach operates at idle, but drops out when you accelerate, check your battery voltage at high speed. If it is above 15.5 volts, all that you have to do is "shunt" the tach with a resister that can be bought at Radio Shack. A 2K ohm resister connected between the ground and pulse poles on the back of the tach will fix the drop-out problem. "
 
" Thanks Bubba,I will look int

" Thanks Bubba,I will look into that. "
 
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