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Author Topic:   Inaccurate tachometer readings
Wild Turkey posted 06-12-2002 10:57 AM ET (US)   Profile for Wild Turkey   Send Email to Wild Turkey  
Last few times out in the Montauk, I noticed the tachometer reading low. Normally WOT is 5500 rpm, sometimes gauge indicates 4300 rpm (WOT) sometimes 5500 (WOT) -- always same top speed by GPS. I replaced tachometer and same problem exists.

Is it the rectifier?? Do I have a big problem here?

whalersman posted 06-12-2002 12:13 PM ET (US)     Profile for whalersman  Send Email to whalersman     
Wild Turkey,
I was having a fit with my Tachometer on my Montauk. The tach would just stop working at RPM's above 4000... Bought a new tach and the new one would work at top RPM's but would stop working at 1000 RPM's just trolling around. I had replaced my Rectifier on my Evinrude a couple of years ago so I did not even consider this at the time. I took the Boat to a dealer and had the charging system checked. He said it checked out fine so we tried another new tach... Same thing... Would stop working at 1000 RPM's after about 5 or 10 minutes..
Anyway, I purchased a new Rectifier, put back in my Original Tachometer, and Replaced the Battery..... Everything is now working fine....
It appeared to be the Rectifier or the Battery.... I'm not going to put in the old Rectifier to find out which componet was causing the trouble...
I hope this helps...
Bigshot posted 06-12-2002 02:28 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Probably rectifier.
88 Montauk posted 06-12-2002 03:05 PM ET (US)     Profile for 88 Montauk  Send Email to 88 Montauk     
What is a rectifier? My Tach recently quit.
whalersman posted 06-12-2002 07:31 PM ET (US)     Profile for whalersman  Send Email to whalersman     
88 Montauk,
A Rectifier is like a Regulator and a Protector for the charging system. The Charging System uses a Stator and is kind of like an Alternator that charges the battery.The Rectifier makes sure the current goes where it is supposed to go and to protect the Stator. My Rectifier was about $40 and a Stator for my engine is about $250.00 plus labor....
Wild Turkey posted 06-12-2002 11:37 PM ET (US)     Profile for Wild Turkey  Send Email to Wild Turkey     
Thanks for the help. After taking a look at the Evinrude tonight, it looks like the rectifier and regulator are one unit. Also, it appears I will have to pull the flywheel to remove the rectifier/regulator.

Is there anyway to test the unit to determine if it is faulty? The motor and electrical systems seem to operate fine right now (except for the tach issue).

Time to call my outboard mechanic?

whalersman posted 06-12-2002 11:54 PM ET (US)     Profile for whalersman  Send Email to whalersman     
Wild Turkey,
The Rectifier is a small round item that bolts on with 2 bolts. It mounts on the starboard side of my 70 HP engine near the wire terminal connection block. Mine has 3 wires coming out of it. Red, Yellow, and a Yellow with a Gray Stripe. My part number for the 1985, 70 HP Evinrude is #583408... Yours might be a little different? It is very easy to change out.
The Stator is the item that lives under the Flywheel and not so easy to remove without the proper tools....
Good luck,
triblet posted 06-13-2002 10:04 AM ET (US)     Profile for triblet  Send Email to triblet     
A rectifer is a sort of one-way valve for
electricity. Electricity can flow through it
one way, but not the other. The alternator
makes AC. By using a rectifier (more likely
four rectifiers in one block), the AC gets
turned into DC.

It is NOT a regulator.


Wild Turkey posted 06-13-2002 11:56 AM ET (US)     Profile for Wild Turkey  Send Email to Wild Turkey     
I agree Chuck... there is a certainly a difference between a rectifier and regulator. I was just stating that they are mounted together in one housing under the flywheel (1989 Evinrude 90hp).


bsmotril posted 06-13-2002 12:04 PM ET (US)     Profile for bsmotril  Send Email to bsmotril     
My tach started doing the same thing when it got condensation inside. It would be flakey in the morning, but start working after the sun shined on it and dried it out later in the day.

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