rectifier bad

studders

Petty Officer 2nd Class
Joined
May 9, 2014
Messages
142
Good afternoon to all. Ive decided to take a look at my brother in laws boat since mine is down for a bit. It is a 1990 javelin 378fs with a Johnson gt 150 vro v6. He tells me that his battery keeps getting drained. Got it home and sure enough you can see the battery volts slowly lowering while it is running. Ive never messed with a outboard as my boat is a I/o. But I think I narrowed it down to the rectifier being bad and draining the battery. Does anyone have a manual or a page on how to replace this? It looks pretty simple but I just want to make sure I get the right part. Also does anyone have a part number or a page to get replacement parts? Another also, where is the oil dipstick or does it even have one to check the oil? Thanks for any info anyone may have.
 

Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,093
rectifier is held by 2 bolts I think? Red, Black, Yellow, Yellow Most outboards use a 3 or 4 gallon oil res. Can see the oil level thru it
 

Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,093
2Q==
 

Joe Reeves

Supreme Mariner
Joined
Feb 24, 2002
Messages
13,262
What is the model number of that engine?

Hopefully you're just joking about the dip stick? That is a 2 stroke engine, is it not? The oil is mixed within the VRO and delivered to the carburetors whereas that mixture is both the fuel supply and the lubricant throughout. For parts, click on "SHOP" at the top of this page... the rest is self explanatory.

I assume that the regulator/rectifier assembly is flawed as you suspect, and if so, I also assume that the tachometer is malfunctioning <-- and if so, pertaining to the tachometer, read and study the following. Also, closely observe the stator under the flywheel to see if a sticky looking substance is dripping from it, dripping down on the powerhead area, and again... if so, that indicates that the stator has overheated due to the regulator/rectifier flaw and will also require replacing.
********************
(Testing Tachometer With Water Cooled Regulator/Rectifier)
(J. Reeves)

A quick check is to simply plug in a another new tachometer as a piece of test equipment. If the new tach works properly and the old tach didn't, obviously the old tach is faulty.... but usually boaters don't carry around a spare tach (see below).

A faulty rectifier wouldn't damage the tachometer, the tachometer simply wouldn't work. This is due to the fact that the tachometer operates off of the charging system and the rectifier converts AC voltage to DC voltage, enabling the charging system. A faulty rectifier disables the charging system, and the tachometer simply doesn't register.

However.... those water cooled regulator/rectifiers that are used on the 35 ampere charging systems (and some others) bring into play a different type problem, and as you've probably found out, they are really a pain to troubleshoot via the proper procedure. There's an easier way.

The tachometer sending/receiving setup operates off of the gray wire at the tachometer. That same gray wire exists at the engine wiring harness which is connected to the engine electrical terminal strip. You'll see that there is a gray wire leading from the regulator/rectifier to that terminal strip, and that there is another gray wire attached to it. That other gray wire is the wire leading to the tachometer which is the one you're looking for.

NOTE: For the later models that DO NOT incorporate a wiring terminal strip, splicing into the "Yellow Wire" mentioned will be necessary.

Normally the Gray wire leading from the tachometer is attached at the terminal strip to another Gray wire which leads from the water cooled voltage regulator/rectifier...... remove the gray wire that leads to the tachometer. Now, find the two (2) yellow wires leading from the stator to that terminal strip. Hopefully one of them is either yellow/gray or is connected to a yellow/gray wire at the terminal strip. If so, connect the gray wire you removed previously to that yellow/gray terminal. Start the engine and check the tachometers operation, and if the tachometer operates as it should, then the regulator/rectifier is faulty and will require replacing. If the tachometer is still faulty, replace the tachometer.

If neither of the yellow wires from the stator is yellow/gray, and neither is attached to a yellow/gray wire, then attach that gray tachometer wire to either yellow stator wire, then the other yellow wire, checking the tachometer operation on both connections.

I've found this method to be a quick and efficient way of finding out which component is faulty.... the tachometer or the regulator/rectifier. It sounds drawn out but really only takes a very short time to run through. If the water cooled regulator/rectifier proves to be faulty, don't put off replacing it as they have been known to catch on fire with disastrous consequences.
********************
 

studders

Petty Officer 2nd Class
Joined
May 9, 2014
Messages
142
What is the model number of that engine?

Hopefully you're just joking about the dip stick? That is a 2 stroke engine, is it not? The oil is mixed within the VRO and delivered to the carburetors whereas that mixture is both the fuel supply and the lubricant throughout. For parts, click on "SHOP" at the top of this page... the rest is self explanatory.

I assume that the regulator/rectifier assembly is flawed as you suspect, and if so, I also assume that the tachometer is malfunctioning <-- and if so, pertaining to the tachometer, read and study the following. Also, closely observe the stator under the flywheel to see if a sticky looking substance is dripping from it, dripping down on the powerhead area, and again... if so, that indicates that the stator has overheated due to the regulator/rectifier flaw and will also require replacing.
********************
(Testing Tachometer With Water Cooled Regulator/Rectifier)
(J. Reeves)

A quick check is to simply plug in a another new tachometer as a piece of test equipment. If the new tach works properly and the old tach didn't, obviously the old tach is faulty.... but usually boaters don't carry around a spare tach (see below).

A faulty rectifier wouldn't damage the tachometer, the tachometer simply wouldn't work. This is due to the fact that the tachometer operates off of the charging system and the rectifier converts AC voltage to DC voltage, enabling the charging system. A faulty rectifier disables the charging system, and the tachometer simply doesn't register.

However.... those water cooled regulator/rectifiers that are used on the 35 ampere charging systems (and some others) bring into play a different type problem, and as you've probably found out, they are really a pain to troubleshoot via the proper procedure. There's an easier way.

The tachometer sending/receiving setup operates off of the gray wire at the tachometer. That same gray wire exists at the engine wiring harness which is connected to the engine electrical terminal strip. You'll see that there is a gray wire leading from the regulator/rectifier to that terminal strip, and that there is another gray wire attached to it. That other gray wire is the wire leading to the tachometer which is the one you're looking for.

NOTE: For the later models that DO NOT incorporate a wiring terminal strip, splicing into the "Yellow Wire" mentioned will be necessary.

Normally the Gray wire leading from the tachometer is attached at the terminal strip to another Gray wire which leads from the water cooled voltage regulator/rectifier...... remove the gray wire that leads to the tachometer. Now, find the two (2) yellow wires leading from the stator to that terminal strip. Hopefully one of them is either yellow/gray or is connected to a yellow/gray wire at the terminal strip. If so, connect the gray wire you removed previously to that yellow/gray terminal. Start the engine and check the tachometers operation, and if the tachometer operates as it should, then the regulator/rectifier is faulty and will require replacing. If the tachometer is still faulty, replace the tachometer.

If neither of the yellow wires from the stator is yellow/gray, and neither is attached to a yellow/gray wire, then attach that gray tachometer wire to either yellow stator wire, then the other yellow wire, checking the tachometer operation on both connections.

I've found this method to be a quick and efficient way of finding out which component is faulty.... the tachometer or the regulator/rectifier. It sounds drawn out but really only takes a very short time to run through. If the water cooled regulator/rectifier proves to be faulty, don't put off replacing it as they have been known to catch on fire with disastrous consequences.
********************

Lol I really was serious about the dipstick. As I stated this is the first time I’ve messed with a outboard. Learn something new everyday. I work on my i/o which has a dipstick and all my buddies have inboards that I help out with and work on. Thanks for all the detailed information. It will really help out when I get back to it tomorrow.
 

Joe Reeves

Supreme Mariner
Joined
Feb 24, 2002
Messages
13,262
Okay... I retired in 1991 and there have been a lot of 4 cycle outboards around lately... so there was a chance that it might have been a dip stick involved.
 

studders

Petty Officer 2nd Class
Joined
May 9, 2014
Messages
142
Okay... I retired in 1991 and there have been a lot of 4 cycle outboards around lately... so there was a chance that it might have been a dip stick involved.

Sitting here thinking about the day and reading your previous message. I’m pretty sure the tachometer was working but I will confirm tomorrow. It would raise when I gave it some throttle and it would idle about 800rpms. Is that still possible if the rectifier was bad?
 

Joe Reeves

Supreme Mariner
Joined
Feb 24, 2002
Messages
13,262
Sitting here thinking about the day and reading your previous message. I’m pretty sure the tachometer was working but I will confirm tomorrow. It would raise when I gave it some throttle and it would idle about 800rpms. Is that still possible if the rectifier was bad?

If the rectifier was bad.... No. However, that regulator/rectifier assembly, if failing, can make weird things happen. As you mention... check the tachometer tomorrow to see if it is erratic.
 
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