Rectifier/Charging/Tachometer problems.

lrice01

lrice01

Petty Officer 3rd Class
Joined
Aug 6, 2005
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75
Greetings good people!<br /><br />I'm a first time poster with a few questions. I have a 1993 Mercury 3 cylinder 75hp outboard. I've done a few voltage checks recommended by Teleflex, because my tachometer is not working. I checked voltage at my battery at idle and with the engine revved up, I can't tell you what the rpms were because of the tach, I'm only reading the battery voltage of 12.2. So it appears that I'm not charging my battery and my tach is not getting the AC voltage needed. I'm thinking, based on the other posts I've read, that I might have a rectifier problem. Any suggestions so that I might confirm positively that it is the rectifier??<br /><br />Thanks.................Lee :confused:
 
Barnacle_Bill

Barnacle_Bill

Admiral
Joined
Feb 8, 2004
Messages
6,469
Re: Rectifier/Charging/Tachometer problems.

Get yourself a manual for that motor and it will tell you how to check the stator and the rectifier. Once you have fixed just one thing using the manual, it has paid for itself.
 
D

Dead Eye

Petty Officer 1st Class
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Jan 21, 2004
Messages
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Re: Rectifier/Charging/Tachometer problems.

Same problem, but different size motor. Replaced the rectifier. no more problem!<br /> Dead eye
 
lrice01

lrice01

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Re: Rectifier/Charging/Tachometer problems.

IBNFSHN,<br /><br />I did just that this morning! I was just hoping to solve the problem as soon as possible. Thanks for your input!<br /><br />Lee
 
lrice01

lrice01

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Re: Rectifier/Charging/Tachometer problems.

Dead Eye,<br /><br />So it was as simple as just replacing the rectifier?? No other electrical problems related to the tach and the charging?<br /><br />Thanks for your comments!<br /><br />Lee
 
L

Laotzu

Petty Officer 2nd Class
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Aug 1, 2004
Messages
150
Re: Rectifier/Charging/Tachometer problems.

Lee, it may be the rectifier, no tach is one of the symtoms. But look around at the other electrical components to see if there are any burnt wires, melted plastics,etc. Something caused the rec to burn out. For instance, when mine burnt, the voltage reg. was also melted.<br /><br />I'm sure you've read on here that you shouldn't rev the motor over 15 to 18k with the muffs on. Tends to blow out pistons, etc.<br /><br />Jerry
 
AMD Rules

AMD Rules

Lieutenant Commander
Joined
Sep 23, 2004
Messages
1,707
Re: Rectifier/Charging/Tachometer problems.

15 to 18k and you'll be picking shrapnel out of your neighbors bushes,,,, lol<br /><br />Keep it under 1500 rpm to be safe. An unloaded two stroke can wind up out of control and cause damage.
 
lrice01

lrice01

Petty Officer 3rd Class
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Messages
75
Re: Rectifier/Charging/Tachometer problems.

Guys,<br /><br />When I revved the engine I was on the water! The rest of the electrical looks fine. I was hoping someone had the info by which I could confirm that it is in fact the rectifier. I have a background in auto mechanics and as such I never was a "parts changer". I prefer to be 99.9% sure before I change out a part.<br /><br />Lee
 
lrice01

lrice01

Petty Officer 3rd Class
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Re: Rectifier/Charging/Tachometer problems.

dakk1,<br /><br />Thanks for the link, unfortunately, I can't open it. Keeps saying website is not available.<br /><br />Lee :(
 
L

Laotzu

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Re: Rectifier/Charging/Tachometer problems.

Sorry, meant 1500, But if you can do 15,000 on the water, get that boat in the hydroplane races.<br /><br />Rectifier test from Clymer manual.....<br />1.disconnect battery<br />2. Using an ohmmeter, connect red lead to ground, black lead alternately to the two stator terminals. Should have continuity<br />3. Connect black test lead to ground, red alternately to stator terminals. Should be no continuity.<br />4.connect black lead to positve terminal on rectifier and red lead alternately to stator terminals. Should have continuity<br />5. connect red lead to positive terminal on rectifier and black lead alternately to the stator terminals. Should have no continuity.<br /><br />Jerry
 
lrice01

lrice01

Petty Officer 3rd Class
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Aug 6, 2005
Messages
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Re: Rectifier/Charging/Tachometer problems.

Jerry,<br /><br />Thanks very much for the diagnostics procedure!<br /><br />I will check it out.<br /><br />Lee
 
lrice01

lrice01

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Re: Rectifier/Charging/Tachometer problems.

Oops!<br /><br />Sorry for the double post!<br /><br />Lee
 
lrice01

lrice01

Petty Officer 3rd Class
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Messages
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Re: Rectifier/Charging/Tachometer problems.

Gentlemen,<br /><br />Thank you for all of your good advice and your suggestions! I purchased a service manual from Mercury and did the following:<br /><br />I checked my battery and charged it as suggested by some good people in some other posts. I found that the battery won't charge up to any voltage over 12.54 volts. Sounds like I need a new battery.<br /><br />I had previously check my voltage at the battery while on the water with the engine running and I measure only 12.2 volts.<br /><br />I checked for AC current at the tachometer and got no reading at all, I assume that is the reason the tachometer does not work. Checked for continuity on the grey "SEND" wire and all is good.<br /><br />Did a visual check on all wiring and all seems fine.<br /><br />Checked the stator per manual instructions and stator checks out ok. Attempted to check rectifier, and found, based on the manual that my outboard's rectifier is incorporated in the voltage regulator. <br /><br />So, based on all of the feedback and the diagnosis that I have performed, it appears I need a new voltage regulator/rectifier.<br /><br />I was wondering if anyone has anymore thoughts, comments etc. Any suggestions where I should pickup another regulator/rectifier, other than Mercury?<br /><br />Thank you again kind people for your time and your generous help!<br /><br />Lee
 
lrice01

lrice01

Petty Officer 3rd Class
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Aug 6, 2005
Messages
75
Re: Rectifier/Charging/Tachometer problems.

I might add, it's a 1994 model and the serial # is 0G013936.
 
lrice01

lrice01

Petty Officer 3rd Class
Joined
Aug 6, 2005
Messages
75
Re: Rectifier/Charging/Tachometer problems.

Guys,<br /><br />Changed the voltage regulator/rectifier today. Now I have charging, the boat was not in the water so I did not rev it to see how high the charging is but I have charging that I did not have before. The tach works, although it's not too accurate, was reading in excess of 2000 rpm's at idle. Definately not idling at 2 grand!!! I will check over the various tach connections and voltages before replacing the tach. Thanks again for all your help!<br /><br />Lee
 
C

callieann

Cadet
Joined
Aug 18, 2005
Messages
8
Re: Rectifier/Charging/Tachometer problems.

Originally posted by Laotzu:<br /> Sorry, meant 1500, But if you can do 15,000 on the water, get that boat in the hydroplane races.<br /><br />Rectifier test from Clymer manual.....<br />1.disconnect battery<br />2. Using an ohmmeter, connect red lead to ground, black lead alternately to the two stator terminals. Should have continuity<br />3. Connect black test lead to ground, red alternately to stator terminals. Should be no continuity.<br />4.connect black lead to positve terminal on rectifier and red lead alternately to stator terminals. Should have continuity<br />5. connect red lead to positive terminal on rectifier and black lead alternately to the stator terminals. Should have no continuity.<br /><br />Jerry
Click to expand...
 
C

callieann

Cadet
Joined
Aug 18, 2005
Messages
8
Re: Rectifier/Charging/Tachometer problems.

Jerry what should a rectifier be putting out on a 40 hp mercury motor. Mine is doing 15.52 callieann
 
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