92 Mercury 50hp stator/rectifier problem

I

Iceman66

Petty Officer 2nd Class
Joined
Jun 30, 2008
Messages
199
Hi
Just bought my self a 92 Mercury 50 hp (3 cyl) that not will pass approx. 2500 rpm.
Previous owner had it to a workshop,they took a compression test(all cyl. well),changed fuelpump,cdi-unit,
rebuildt the carbs,then the owner stopped them cause it started to be expencive.

Have set the ignition timing correct,so the engine runs really great at idle speed now.Fore some reason I dont now ,the workshop had put the timing way out.


I suspect stator faullt,understand that the stator on this engine has one low speed and one high speed winding,
is this correct?
Have measured the stator all way,every value is fine except between the two yellow wires that was connected to the
small type rectifier,value here(0.5 ohm) was 3 times more than the specifications chart says.
The stator has been replaced before I guess,partnumber is 174-9710 K
So I wonder,if using this 16 amp stator, I meen a voltage regulator/rectifier should be wired in somewhere,right?

This engine has just a small rectifier and output here is way to much(16-17 V) at idle speed.

Have not run the engine with load(out at sea) yet.


Could the wrong ignition settings cause this?
Do I need a new stator and/or a voltage/rectifier?

What should I do,anyone here that can help?

(Forgive me if the english is bad,am a Norwegian)
 
L

Laddies

Banned
Joined
Sep 10, 2004
Messages
12,218
Re: 92 Mercury 50hp stator/rectifier problem

If the timing is to slow or the trigger is stuck in the retard the engine will not rev, if you think the stator is causing the problem disconnect the yellow wires from the rectifier and tape them off and see if it runs properly with them disconnected. That is a 16 amp stator and needs a regulator.
 
j_martin

j_martin

Admiral
Joined
Sep 22, 2006
Messages
7,474
Re: 92 Mercury 50hp stator/rectifier problem

The charging circuit is fine. (yellow wires and rectifier) The battery and connections are suspect, as they should hold down the voltage to about 15V max.

The charge coils, driving the switchbox (probably what you called the cdi) need to be measured with a DVA, which is a peak reading voltmeter. A plain multimeter will not do for the voltage readings.

There may or may not be other modules in the bias circuit that will affect performance. Most can be just disconnected for testing.

If they missed the ignition timing, all their work is suspect.

(edit) Try the yellow wire disconnect said in the post before this. Might be significant.
 
J

James R

Commander
Joined
Feb 1, 2007
Messages
2,664
Re: 92 Mercury 50hp stator/rectifier problem

Laddies almost had it, or maybe he did. Disconnect the rectifier and do an ohm's check on it. I'll bet that it is Kaput. If it is then replace it and all will be well.
 
L

Laddies

Banned
Joined
Sep 10, 2004
Messages
12,218
Re: 92 Mercury 50hp stator/rectifier problem

His rectifier is working as he said it's putting out 16 to 17 volts at idle, it's a 16 amp stator that needs a regulator or heavier duty battery as J Martin said and I also agree that the workshops, work needs to be checked closely.
 
I

Iceman66

Petty Officer 2nd Class
Joined
Jun 30, 2008
Messages
199
Re: 92 Mercury 50hp stator/rectifier problem

Did the Ohm`s test on the rectifier,its "GONE",need to replace it.

Can i use the same type rectifier, doesn`t this small type just change the AC-volt into DC-Volt or does it regulate the Volt too?

On Ebay the seller has a important note about the 174-9710K stator that says: DO NOT USE WITH A RECTIFIER ONLY.
* ALL 16 AMP OR HIGHER STATORS REQUIRE AVOLTAGE REGULATOR.


Can this have something to do with the rpm issue,since I have just a rectifier,or is it something that is just bad fore my battery?

What about the value between the two yellow wires:0,5 OHM ,Manual says slighty lower,
do you think the stator is ok or?
 
I

Iceman66

Petty Officer 2nd Class
Joined
Jun 30, 2008
Messages
199
Re: 92 Mercury 50hp stator/rectifier problem

Found this interesting information according to the 174-9710K stator by CDI-Electronics: High speed miss or weak hole shot:
1. Connect DVA meter to the blue and blue/white wires and do a running test. The voltage should show a smooth climb and stabilize,
gradually falling off at higher RPM's (above 3000). If you see a sudden drop in voltage right before the miss becomes apparent, the
stator is likely at fault. Repeat the test for the red and red/white wires. There should be a smooth climb in voltage with no drop at all
up to wide-open throttle.
2. Connect DVA meter to the red and red/white wires. The voltage should show a smooth climb throughout the RPM range, a sudden
drop or decline in voltage indicates a problem usually found in the stator, although a rectifier can cause the same symptom.
3. Disconnect rectifier/regulator and retest. If the problem disappears, replace the rectifier/regulator and retest.
4. For a high speed electrical miss, rotate the stator one mounting hole and retest. If the miss is still present, the stator may be bad.

So clearly the first thing to do is run the engine at sea with the two yellow stator-leads disconnected,if problem is gone, buy a new
voltage regulator/rectifier.
If the high speed rpm still is missing,a new stator and a new voltage/rectifier has to be bought.

Agree?
 
L

Laddies

Banned
Joined
Sep 10, 2004
Messages
12,218
Re: 92 Mercury 50hp stator/rectifier problem

Isn't that what I said in the first post?
 
I

Iceman66

Petty Officer 2nd Class
Joined
Jun 30, 2008
Messages
199
Re: 92 Mercury 50hp stator/rectifier problem

Laddies said:
Isn't that what I said in the first post?
Click to expand...

You are quite right.

May take some time before I can do this test,cause here in Norway it is still very cold(below zero),
so I guess I will wait some weeks .
I will reply in the thread when done.

Many thanks to you and all others fore the good words and knowledge.
 
I

Iceman66

Petty Officer 2nd Class
Joined
Jun 30, 2008
Messages
199
Re: 92 Mercury 50hp stator/rectifier problem

Have tested at sea today,with the two yellow stator wires disconnected,same problem.
Did a multimeter-test on the stator,do have full continuity between them,is this correct?
The resistance between them are 0,5 ( The specifications in the service manual says 0,16-0,19)

Any thougts about what to do now?
 
C

CharlieB

Vice Admiral
Joined
Apr 10, 2007
Messages
5,617
Re: 92 Mercury 50hp stator/rectifier problem

Many times an Ohms test alone will not prpove the fault well enough and you may replace an electrical part and NOT cure the problem.

A DVA test absolutely proves one way or the other, with NO doubt.

Find a DVA meter or a DVA adaptor to use with your Volt/Ohm meter and test that stator as described in the CDI manual.

You can build a DVA adaptor quite simply and cheaply.

http://forums.iboats.com/mercury-ma...e-dva-adapter-standard-multimeter-374544.html
 
I

Iceman66

Petty Officer 2nd Class
Joined
Jun 30, 2008
Messages
199
Re: 92 Mercury 50hp stator/rectifier problem

CharlieB said:
Many times an Ohms test alone will not prpove the fault well enough and you may replace an electrical part and NOT cure the problem.

A DVA test absolutely proves one way or the other, with NO doubt.

Find a DVA meter or a DVA adaptor to use with your Volt/Ohm meter and test that stator as described in the CDI manual.

You can build a DVA adaptor quite simply and cheaply.

http://forums.iboats.com/mercury-ma...e-dva-adapter-standard-multimeter-374544.html
Click to expand...


I will get my self a DVA meter or a DVA adaptor to my multimeter, and some piercing probes and do a DVA-test.

Just to be sure,do I set the meter to 1000Vdc or 1000Vac when doing the drop voltage test on the stator? The drawing in your link
says 1000Vdc,the CDI manual says nothing about this,I thought the stator produced ac at the red and blue wire.

Sorry for asking so much, but I am a amateur in the beginning of understanding this electronic things, mecanic has been
mine tasks until now.
 
C

CharlieB

Vice Admiral
Joined
Apr 10, 2007
Messages
5,617
Re: 92 Mercury 50hp stator/rectifier problem

600 AC Max output so the 1000VAC scale will be fine
 
I

Iceman66

Petty Officer 2nd Class
Joined
Jun 30, 2008
Messages
199
Re: 92 Mercury 50hp stator/rectifier problem

CharlieB said:
600 AC Max output so the 1000VAC scale will be fine
Click to expand...

Have studied the CDI-troubleshooting guide some more and it says:
When using a DVA-adapter,a digital meter must be set to its DC voltage scale.Peak AC voltage is the measurement,but
the DVA-adapter has a built-in bridge rectifier,which converts AC to DC. The DC voltage setting on a digital meter is required
to accurately read DVA.

I will either get/build me an adapter and use my own meter, or borrow a pro meter from a friend at work,he garanties his meter is capable to read DVA,he even says that he can logg all the results and connect it to a computer reading a lot of values.
Guess I have to trust him.

Will reply when test is done.
 
I

Iceman66

Petty Officer 2nd Class
Joined
Jun 30, 2008
Messages
199
Re: 92 Mercury 50hp stator/rectifier problem

(Stator:174-9710K)
Stator Resistance: Low speed: 523 high speed: 27.9

Stator DVA-values(peak) are : 216V / 274V------------------------- 54V / 49V
---------------------Low speed: conn / disc ------------high speed: conn / disc

Trigger resistance : cyl.1 2 3

1182------------ 1191--------- 1167



Trigger DVA-values(peak) are:cyl. 1 2 3

1.2V 13.5V-------------- 1.2V 13.1V------------ 1.3V 13.8V
conn / disc-------------- conn / disc ------------ conn / disc



Trigger values without the peak-reading: cyl.1 2 3

2.0V 3.9V----------1.9V 2.2V---------- 2.2V 3.9V
conn / disc ------ conn / disc--------- conn / disc


Do I have a Trigger/stator problem here or?

Just fore the rec:Engine runs smooth and idles nice,it just won`t pass appr.2800-3000 rpm.
New fuelpump
New Cdi-pack
Carbs rebuildt


I am not giving up yet,but I have to admit,I am getting some new grey hair trying to solve this problem.

Could this be a reed-problem?
Suggestions?
 
You must log in or register to reply here.
Top