92 Mariner EFI 175 Magnum voltage issue

eng208

Seaman
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Jul 8, 2012
Messages
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I've got an issue with voltage issue on an old 92 Mariner Magnum EFI. It is the same as the Mercury Black Max 175. Anything below 2300 RPM and the voltage is erratic, going from 10-14 rapidly. Above 2300, and voltage stays at about 14 v. Any help as to what this issue might be? I have intermittent hard starting problems after it gets warm also and idle drops after heating up to operating temp. When cold, it starts easily and runs smooth, just has this voltage issue.

 

Prophammer

Chief Petty Officer
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Check the easiest stuff first, how good is the battery, wire connectors tight with no corrosion etc, it's a complicated machine , don't let it It overwhelm you, check the obvious first, the more complex systems check by process of elimination, stator ,voltage , regulator, it's all I can think of , good luck
 

eng208

Seaman
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I have a manual and will look at some of these things tomorrow. Any easy way to check the regulators? Not even sure where they would be.
 

eng208

Seaman
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I pulled the manual and started testing per the manual. I got to the voltage regulators and checked the two short yellow wires. According to the manual, it should be no resistance across these. On the stator side, I do have no resistance but on the voltage regulator side, I have about 1700K ohms. Really friggin high. The diode check failed also. It showed open. Is there someone that can confirm this is the correct test before I spend 400 dollars on two regulators?
 

sam am I

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DON'T spend that much.......geeesh.

These are spot on "line and load regulation" (spec'd as good or better than OEM, better IME), been running same ones for years now, no problems, run three batteries.........
http://www.amazon.com/gp/product/B00...2AEKKX8E6W98JK

voltage-regulator-9-638.jpg
Don't be baffled by the BS'ers out there (whom most likely re-brand these anyway), this is all you need to know and the most important two factors with voltage regulator's second to how long they'll run.......which I have two or three years on the same ones now. Tach output steady as a rock as well....

Check bullets connectors etc, if loose/corroded you can get that. If that was problem, cut off the bullets and solder. If connectors are all clean and tight and issue persists replace at $40/ea. and buy a spare or two that you'll never use
wink.gif
 
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eng208

Seaman
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WOW! It shows as a replacement for mine. Being a 815279T I think. However, mine has a purple wire coming out of it and I only have one big unit where I have seen two regulators bolted on other engines. Can you help me out with this?
 

eng208

Seaman
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Just pulled this regulator off. It is a 18736-C. Looks to be 500.00 if I can even find one! It is molded to fit into the cooling passage.

Why me??
 

eng208

Seaman
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I did some searching, and there is a kit to replace this unit with a plate and two of the standard rectifiers. I wonder if I can find a plate by itself. Then I could order the regulators from Amazon.
 

eng208

Seaman
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That is correct. I have found out it is called the 40 AMP water cooled rectifier/regulator and wouldn't you guess it? Mercury quit using them in 91. I guess my motor is a 91 on a 92 boat. I found CDI's replacement upgrade kit for 517. That would upgrade the stator and regulators with new CDI units. Or, for 385, I can order the CDI replacement water cooled unit and take a chance with my stator, which is original and 25yrs old. Then I would have to buy a stator and stick with the two wire which costs about 395. Seems a no brainer to replace with the complete upgrade CDI kit..... Any suggestions?
 

eng208

Seaman
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That is correct. I have found out it is called the 40 AMP water cooled rectifier/regulator and wouldn't you guess it? Mercury quit using them in 91. I guess my motor is a 91 on a 92 boat. I found CDI's replacement upgrade kit for 517. That would upgrade the stator and regulators with new CDI units. Or, for 385, I can order the CDI replacement water cooled unit and take a chance with my stator, which is original and 25yrs old. Then I would have to buy a stator and stick with the two wire which costs about 395. Seems a no brainer to replace with the complete upgrade CDI kit..... Any suggestions?

http://www.lowcostboatingstore.com/...Mariner-Stator-Kit--6-Cyl-40-Amp_p_37895.html
 

sam am I

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yes, hang on......You could try this. Because they are all just air cooled these days. (which is what the kits contains, two air cooled types)

Get the plate or make a plate to block off the water cooling jacket and buy two of the 20Amp at the link above (same as what the kit has) and parallel them.

The 20Amp's outputs are all run in parallel these days (mine included) to form the 40A total. And that's what the kit will have you do............parallel the outputs

My only unknown is paralleling the inputs. Normally and as stated you need a 4 yellow wire stator to equally limit the saturating coils at 20Amps to each reg..thus not over loading a 20Amp reg

Your 2 yellow wire is 40Amps, paralleling the inputs should share current if the reg's are close in design, which they most likely are within 5% tolerance of one another.

BUT if not close in design, one reg might take 30 and the other 10 during a full'ish load of say 40Amps.......the work around? Measure it and see, if it work, protect it and run it.

http://www.********************/sea-d...ers-79231.html

where ***** = w h o l e s a l e m a r i n e

I'd put a resettable 20A breaker on the inputs ( I run these now on my inputs), fire it up, load it down with a 40A @ 12VDC load and use a clamp on current meter and see just what each input is drawing, if they're both at about 20A........leave the breakers inline and run'um.

Else bite the bullet looks like, get the kit (4 yellow wire stator and 2-815279T and plate and be done
 
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sam am I

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Cost ya $80 in regs' with a plate to see......if the current is too offset to one reg, the reg's are of course the same as in the kit, so no loss to see, just buy the stator at that point and your still saving money
40A Stator.jpg
 
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Faztbullet

Supreme Mariner
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Mar 2, 2008
Messages
15,644
Because they are all just air cooled these days
This model V-6 regulator mounts on the divider plate with thermal compound to draw away heat from rectifiers, that why it used a water cooled unit due to its 40amp 2 wire output.
 

sam am I

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That is awesome! I will look into it.


Let us know............Oh, mount the reg's close to one another and/or close to each other on the same piece of metel/alum. As they heat up, ya want the inherent thermal characteristics to track each other closely. Keeps um matched better
 
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sam am I

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This model V-6 regulator mounts on the divider plate with thermal compound to draw away heat from rectifiers, that why it used a water cooled unit due to its 40amp 2 wire output.

Yeah I sorta figured that, the single unit probably got pretty warm. Breaking it in half allowed for air cooled/heat sunk units but, probably over all wattage/mass of the two grew over the single 40A I'll bet. It's Interesting (to me anyway) seeing the designs over the years de/evolved........
 
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sam am I

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eng208,

Little bit more thinking on this, slow morning :sleeping:

If the two work with their inputs paralleled, there is no reason then three in parallel won't work either. (the computer simulations say both will work BTW), There is also plenty of mounting room for 3 in a row.

Thoughts are......

The 40A divided by 3 will give even more forgiveness on tolerance differences when at max load...e.g.,....You can't necessarily end up with something like 23A/17A, it'll force it to something like 17A/14A/9A for example with three of them waaaaaaaay out of whack. I'll bet though it'll run something like 14A/15A/13A worst case max'd out.

The reg's, in general, by design have to be reasonably tight tolerance right now anyway because the same can be said and applies for paralleling the outputs ("sharing load current reasonably equally due to the units are/stay closely **matched**") and given that.......then "load regulation" is of course directly reflected to the input current draw!!

They are (and still at merc I think), in fact still paralleling the outputs in aftermarket and in kits, the reg's probably, as i guessed earlier, have a 5% to 10% spec., three in parallel at $120 total + plate should run flawless.

**These units use a sensing wire (male bullet) for negitive feedback (they run in/as a closed loop system)**


3 regs.jpg
 
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eng208

Seaman
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Jul 8, 2012
Messages
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But a new stator runs right at 400.00 for the 4 wire. And like I said, the stator on my unit is 25 yrs old. So if I spend the money on the two or three regulators, then have to buy a stator, I am at the same price as if I fix it right to begin with. The more I think about it, the more I am probably just going to go ahead and by the CDI upgrade kit. The fact it regulates good above 2300 rpm is confusing to me though. It's like the voltage is too unstable or something is trying to pull the voltage to ground (actually goes to about 10 volts and then back to 14) below 2300 RPM. I'm concerned the stator may be a problem too.
 
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